Manual of Field Adjustments - Antique Surveying Equipment

Manual of Field Adjustments - Antique Surveying Equipment
Manual of Field Adjustments
\| American Made — American Style
| Y |
berger instruments
Price $2.95
You Own A Great Instrument! |
Favorites on surveying and construction sites for more than a cen-
tury, Berger instruments are built better to last longer — to help you
achieve lower costs and speedier completions.
Designed and fabricated to meet the job challenges of the future, every
Berger model offers maximum performance and value for your instru-
ment dollar. And, there’s a full range of Berger models to choose from and a
model that's precisely right for your needs and for your budget.
50 whether you're grading, leveling, aligning, turning angles — build-
ing single-family units, apartments, or large commercial projects -— there's
a Berger available to help you to reduce costly measuring errors and expen-
sive rework.
Berger instruments are better in many important ways. Get behind
one. Take a look. You'll welcome the exceptionally clear optics — cross
hairs that are sharp and distinct, smooth dependable controls and a host of
other features that make Berger instruments the finest in their class.
For example, vernier and circle graduations are clear, permanent and
accurately registered on metal so it takes just seconds to line up for precise
Finishes are tough, hard-baked, extra durable for stronger impact abra-
sion resistance. Materials (only the best have been used); special aircraft
aluminum alloys; brass, bronze and steel, sterling silver, to make sure that a
Berger keeps working day in and day out.
Above all, Berger instruments are engineered to be easy to use and
simple to maintain.
Leveling screws are large — so you can work even with gloves on, and
circles and verniers are Sized to speed readings and prevent errors.
But, there's even more to a Berger. . .
Level vial mountings are of the most up-to-date design to make sure that
your instrument holds its adjustment in the field.
Tripods are of proven standard and wide frame designs [or greatest
stability and strength.
And, to help you keep your Berger in good order and free from
damage, every Berger instrument is packaged in a unique, specially
designed and custom-tooled, highly protective, maximum visibility,
yellow ABS case with full polyethylene foam insert or a custom crafted
mahogany case with fitted retainers.
Finally, there's the company and the people behind the product . . .
experienced, caring craftsmen who constantly strive to produce the better
instrument . . . the instrument that's made to last and to be the favorite on
your job. Try a Berger today!
All instruments and accessories shown and/or described in this
manual are designed and manufactured to exacting standards by
American Craftsmen in Boston, MA, U.S.A.
The manufacturer reserves the right to change specifications and prices
without notice. :
Table of Contents
| Berger Engineers’ Transits and Levels, Specifications and
II Use and Care of Instruments
A. Use of the Tripod
B. Fastening the Instrument to the Tripod
C. Leveling the Instrument
|. Transits
2. Dumpy Levels
D. Setting up the Optical Plummet Transit
E. Use of the Transit with Beaman Stadia Arc
FF. Use of the Stadia Reticle
G. Carrying Instruments
H. Specific Parts of Transits and Levels, Use and Care
. Transit Compass
Level Vials
Levelling Screws
. Carrying Case
III Adjustments of Instruments
A. Repair Shop Adjustments
B. Adjustments of the Transit Which Can be Made in the Field
I. Plate levels
. Collimation
Erecting Telescope
. Horizontal Axis
Telescope Level
Vertical Arc
. Yertical Circle
. Vernier Level
10. Interchangeable Auxiliary Telescope
Il. The Level
C. Adjustments of the Dumpy Level Which Can be Made in the Field
|. The Level
2. Horizontal Cross-hair
3. The “Peg” Adjustment
4. The Second Method
[Y Parts List
V Packing and Packaging for Shipment
VI Berger Reticles, Leveling Rods and Tripods
oe, J LE
| 2
Berger Instruments
“Power Zoom optional, extra,
— ни
Model Bronze Astron Polara Project _
Horizontal Circle Diameter в 614 inches Bla Inches 614 inches 513 inches 5'5 inches
Horizontal Vernier Reading See Next Page See Next Page ___] See Next Page See Next Page | See Next Page
Telescope Length 1115 inches 11% inches 10% inches 101 inches 1012 inches
Telescope Power | 26x es 22x 22x 22x
Effective Aperture 1.430" (36.3 mm) | 1.4" (35.6 mm) 3" {33 mm) 1.3" (33 mm) 1.3" id ma —
Exit Pupil 055” (1.4 mm) 055” (1.44 mm) 062" (1.5 mm) 062" (1.5mm) [| 062” (1.5 mm)
| Resolving Power | 34 seconds 4 seconds 415 seconds 4'z seconds 41 coors
Minimum Focus 134 4 ft uz SE. ОЗ 3 ft. 3 ft,
Field of View TE 1° 6 = 1° 24 1° 24 1 24
Vertical Circle Diameter — | 5inches “5 inches 5 inches 5 Inches 5 inches
Vertical Circle Graduations | 30 minutes 30 minutes 30 minutes 30 minutes 30 minutes
Vertical Vernier Reading 1 minute 1 minute 1 minute 1 minute 1 minute
‘Telescope Level Vial - e ÉL e ll
ZF Sensitivity 25 secs./2 mm div. 40 secs.;? mm div. | 40 secs? mm div. | 40 secs./2 mm div. 50 secs./2 mm div.
| Length 4-29/32" 4-29/32" 4-29/32" 4-116" 4-116" 0
| Plate Vials (2) Sensitivity | 65 secs? mm. div, B0 secs/2 mm div. | 80 secs..2 mm div. | 80 secs./2 mm div. ‘120 secs./2 mm div.
É Length - Front | 2-1/16" 2-1/32" 2-1/32" 2-1/32" — 21/97
Side | 2-11/167 2-11/18" 2.11/16 2.1/32" — | 21/87"
| Compass Needle Length Fa inches Jz Inches 37 inches 3-1/16 inches ps 3-1/16 inches
Compass Graduations 20 minutes 30 minutes 30 minutes 30 minutes 1 degree
Power Zoom Range’ 20x to 36x "20x to 36x — | 20x to 36x 18x to 34x 18x to 34% He
Approximate Shipping Weight 36 lbs. 42 Ibs 41 165. 33 Ibs. Е 33 lbs.
Horizontal With 1115" | With 1012"
Circle Verniers Telescope | Telescope
Grad. To Read To Model No. | Model No.
r 30 minutes 1 minute 65-816
Bronze Transit with Compass 20 minutes 30 seconds 65-813
15 minutes 20 seconds 65-812
1 к © 30 minutes | minute 65-836
Bronze Transit with Compass 20 minutes 30 seconds 65-833
and Beaman Stadia Circle 15 minutes 20 seconds 65-832
30 minutes 1 minute 67-816 62-816
Astron Transit with Compass 20 minutes | 30 seconds 67-813 62-813
15 minutes 20 seconds 67-812 62-812
30 minutes | minute 67-836 62-836
Astron Transil with Compass | 20 minutes 10 seconds 67-833 69-833
and Beamarhgee = Circla 15 minutes | 20 seconds 67-832 62-832
Folara Transit with Compass 30 minutes 1 minute 37-216
Polara Transit without Compass | 30 Minutes | minute 57-916
Project Transit with Compass 30
and 1 Double Vernier BLL 1
Project Transit with Compass |
JU minutes
| and Double Opposite Verniers TA 102
Other types of graduations to suit individual preference or requirements are available
Many of these can be furnished without extra cost. Specify type desired and request quotation
Telescope Length
18 inches
18 inches
Objective Lens Diameter
2 inches (508 mm)
2 inches (50.8 mm)
Efféctive Objective Aperture
1.921 inches (48.8 mmi
1.321 inches (48.8 mm
Exit Pupil Diameter
Telescope Magnilying Power
055 inches {1.37 mm)
Uso mech (1.37 mm)
Fiald of View
1 degree, 4 minutes
| degree, 4 minutes
Resolving Power
6 seconds
2.6 seconds
Eye Relief
400 inch 10.2 mm
400 inch 110.2 mm
Minimum Focus
9 feet
ÿ feet
Telescope Level Vial Length
a inches
734 inches
Telescope Leve! Vial Sensitivity
20 seconds per 2 mm div
10 seconds per 2 mm div
Specifications subject to change without notice.
Objective Lens Achromat Achromat
Eye Lens Achromai Achromat
Approximate Shipping Weight 25 Ibs 25 Ibs
The engineers and constructors who are changing the face of America have
one thing in common. They rely on Berger engineers’ struments to get the big
job off to a fast accurate start.
Why a Berger? Get behind one and you'll see: the clear, sharp image, free of
any chromatic or spherical aberration . . . the unvaryıng true line of collimation
. . . the smooth-focusing action of the telescope with easy meshing rack and
pinion — no binding or side-play . . . no backlash. And note how freely a Berger
rotates on its centers without fretting or binding, whatever the variation in
climatic conditions .. . and how perfectly positioned and positive are the
These are features you'll find in all Berger engineers’ mstruments
features that make Berger such a favorite with the men and with the companies
that have guided some of the major construction projects of the century,
When there's no margin for error . . . they rely on a Berger. After you ve
used one . . . you'll know why.
65 and 67 Series
All the features of the standard models plus the advantages of optical
Berger Optical Plummet Transits provide the ultimate in speed and accuracy
when setting up over a specific point. The use of an optical line of sight through
the instrument center and a tripod which enables a shifting of the instrument offers
maximum efficiency in cases where multiple set ups must be made or when wind
conditions are a factor. |
Berger Optical Plummet Transits are especially designed for durability and
ease of use. The plummet telescope is set at a 45° angle to the horizontal plate so
that the user need only bend his head to view the cross hairs and point. Centering
accuracy is readily determinable by rotating the upper portion of the transit about
its axis. The Optical Plummet 15 approximately 4 power and focuses from 18" to
infinity. The reticle supplied 1s of a cross lines and circle type. Individual focus
for reticle and ground.
The Berger Lateral Adjuster Shifting Head Tripod (used in conjunction with
OP transits) allows the user to shift his instrument approximately 2” in any
direction, The shitting head 1s meticulously manufactured to assure that there will
be no significant change in the level condition of the instrument while centering
over the point. Any sight through the plummet will therefore be perpendicular to
the level of the instrument. The shifting head surfaces are coated with a special
hard abrasion resistant Teflon™ material providing a smooth shding action
during use.
* Reg. Trademark of DuPont
65 Series
As fine an engineering instrument as expert design, skilled craftsmanship and
superb materials can achieve.
All of its features are skillfully combined to produce an instrument which is
world-famous for its ability to provide a lifetime of accurate trouble-free service.
Achromatic optical system; fully enclosed 3/8" x 32 thread, nickel silver leveling
screws, hand fitted into replaceable bronze bushings; reversion type telescope
vial; sterling silver circles and verniers with hinged shade frames. Horizontal
circles have two rows of figures in opposite directions 07-360” and 360%-0”.
Figures inclined in the direction they should be read; double opposite verniers.
Vertical circle has one double vemier, protected with removable guard.
Bronze tapered repeating centers are hand lapped to precise fit. Hand fitted
nickel silver tangent screws have 1/4” x 40 thread. Forged brass foot plate with
315" x 8 thread. Choice of spiderweb or glass reticle with cross and stadia wires at
|; 100),
Carrying case, sunshade, 12 oz. Berger Retracta-Bob™*, magnifier,
adjusting wrenches, screwdriver and Field Adjustment Manual. Instrument
finished in baked, non-reflecting, black wrinkle enamel. Use with tripod
Models 841, 842, 843 or 844. «„ Putent Pending
67 Series
A mid-priced, top performing instrument of advanced design, high
quality and rugged construction, Bronze * U' type yoke frame with wye
bearines. Precision turned and hand lapped repeating centers of long wear-
ing bronze alloy. Fully enclosed 3/8" x 32 thread nickel silver leveling
screws in hand fitted replaceable bronze bushings. Nickel silver 14” x 40
thread tangent screws with wear takeup adjustment. One piece erecting
achromatic telescope with internal rack and pinion focusing. Spider web or
glass reticle with stadia wires at ratio of 1:100. Horizontal circle has two
rows of figures in opposite directions, (°-360° and 360°-0°, inclined in
direction they should be read; double opposite verniers with hinged shade
frames. Vertical circle with one double vernier, protected with removable
puard. Graduations on corrosion resistant aluminum alloy. Forged brass foot
plate with U.S. Standard 314” x 5 thread.
Carrying case, sunshade, 12 oz. Berger Retracta-Bob™, magnifier,
adjusting wrenches, screwdriver and Field Adjustment Manual. Instrument
finished in baked black wrinkle enamel. Use with tripod Models 841, 842,
843 or 844.
57 Series
An all-around utility transit at a budget price. Exceeds government
specifications for a 5%" transit reading to one minute. One piece erecting,
achromatic telescope with interior rack and pinion focusing. Spiral focusing
eyepiece. Spider web reticle with stadia wires at ratio of 1: 100 (glass reticle
extra). Horizontal circle with two rows of figures in opposite directions,
0°-360° and 360°-0°. Double opposite verniers. Vertical circle with one
double wvernier, removable guard. Graduations on corrosion resistant
aluminum alloy. Tapered, repeating centers of bronze alloy — hand lapped
and precisely fitted. Nickel silver tangent screws with 14" x 40 thread. Fully
enclosed nickel silver leveling screws with 38"" x 32 thread, hand fitted into
replaceable bronze bushings. Forged brass foot plate with U.S. Standard
312" x 8 thread.
Carrying case, sunshade, 12 oz. Retracta-Bob™, magnifier, screw-
driver, adjusting wrenches, and Field Adjustment Manual. Instrument
finished in baked black wrinkle enamel. Use with tripod Models 841, 842,
843 and 644.
Series 100 and 102
A quality American Made 5% Transit for the cost conscious construc-
tor, Accurate and versatile — rugged and dependable.
Will perform all the functions of horizontal angle setting and measuring
as well as leveling operations ordinarily required of a one-minute transit.
Model 100 with one double vernier reading to one minute; Model 102 with
two double opposite verniers to 1 min. Vertical Circle is 5 inches in diameter
with one double vernier reading to one minute.
Features reinforced bronze standards, special corrosion resistant aircraft
aluminum alloy circles and verniers, Asarcon inner center, coated, color
corrected lenses, Telescope is 22 power with stadia lines at 1:100 ratio.
Power Zoom 18X-34X available at extra charge. Supplied with carrying
case, sunshade, 12 oz. Berger Plumb Bob, magnifier, adjusting wrenches,
screwdriver. Use with tripod Models 821, 822, 841, 842, 843 or 844,
45 Series
Berger developed this instrument to overcome the many problems en-
countered in underground surveying, 8%" erecting, internal focusing, 18
power optical system with short focus of 2-1/3 feet. Stadia lines at ratio of
1: 100.
One piece bronze **U"" type yoke frame. 415" diameter horizontal circle
(sterling silver) with two rows of figures 0°-360° in opposite directions.
Double opposite vermers read directly to one minute, Shade frames with
4 diameter vertical circle with one double vernier (sterling silver) reads
directly to one minute.
4-1/8" long reversion type level vial of 45 seconds sensitivity per 2 mm
2 plate levels of 75 seconds sensitivity per 2 mm div. Nickel silver
leveling screws.
Nickel silver tangent screws. Bronze, tapered, repeating centers are
hand lapped and fitted.
Finished in baked black wrinkle enamel.
Forged brass foot plate with 214” x 10 threads.
Compass reads directly to 30 minutes with 2-5/8" needle.
Furnished complete with carrying case, sunshade, 12 oz. brass plumb
bob, magnifier, spanner wrench, screwdriver and Instruction Manual.
Choice of special full length tripods or 1/2 length versions,
Models 05-700 and 05-700-10
Outstanding accuracy and performance under all conditions of use in-
cluding extremes of heat, cold and dusty locations.
Erecting, interior focusing optical system, two-inch achromat objective
lens (one of the largest available) and achromat eye lens provide exceptional
brilliance of image, wide field of view, large exit pupil diameter and
unusually high resolution. Coated lenses for maximum light transmission
and minimum reflectance.
Eye relief of almost one-half inch aids in comfortable viewing. Carefully
fitted bronze focusing slide maintains true line of sight throughout entire
focusing range. Spiral focusing eyepiece with reset scale, permits instant
return to the proper setting for your eye.
36 power magnification. Plain cross wires in a choice of spider-web or
glass reticle, Stadia wires available at shght extra cost.
The conical spindle is a special bronze alloy noted for its stability and
long wearing qualities. It is machined to an accuracy of 000050" (fifty
millionths of an inch), then carefully hand lapped and fitted to its bronze
leveling head. Integral telescope and flexure-proof level bar of high
strength, heat treated aircraft aluminum alloy.
Precision ground level vial (20 seconds per 2 mm div. on Model 05-700
and 10 seconds per 2 mm div. on Model (05-700- 10) 1s nested inside the bar
for protection. Assembly, spring loaded at one end 1s adjustable by a single
capstan nut. Drain and ventilation ports in the level bar allow air circulation
around the level vial and dissipation of rain water.
Nickel silver leveling screws with 3/8” x 32 threads hand lapped and
fitted to replaceable bronze bushings. Precisely fitted nickel silver tangent
screw with 14” x 40 threads with take-up adjustment for wear, has bronze
helical spring with counter-motion. Forged brass foot plate with U.S.
Government standard 3142” x 8 threads. Finished in baked black wrinkle
Fitted carrying case with sunshade, screwdnver, adjusting wrenches and
Field Adjustment Manual. Use with tripod Models 841, 842, 843 or 844.
To obtain the greatest possible service from your finely constructed
engineering instrument, take good care of it, follow the instructions in this
manual and should repairs be necessary, entrust it only to the factory or to a
qualified service center. Your instrument has been precision built to provide
good and lengthy service provided you follow these basic rules setting up
and leveling.
A. Use Of The Tripod
Your Berger tripod is designed to provide a solid, steady support for
your instrument. Extension leg models are adjustable for leg length and
are recommended for convenient transport and for use on rough, highly
irregular terrain.
When setting up the tripod, it is advisable to place the tripod legs
about 30 inches apart and initially set the tripod so that the top of the
tripod is nearly level. Be sure that the tripod leg clamps are firmly
tightened and that provision is made to prevent slippage by pressing the
tripod points firmly into the ground. On hard surfaces, such as concrete,
small pockets should be chiseled into the concrete to secure the points.
Another (and safer) method is to use the chain restraint assembly avail-
able as an option.
B. Fastening The Instrument To The Tripod
The instruments in this manual are
fastened to the tripod by threading the
leveling screw foot plate on to the top
of the tripod head. The mounting
should be done carefully to avoid
crossing threads and the footplate
must be firmly screwed onto the
flange of the tripod head. Be sure that
the plumb bob chain and hook hang
freely through the tripod head.
(Fig. 1). Fig. 1
C. Leveling The Instrument
|. Transits. To level a transit with a four screw leveling head follow this
procedure: Set the tripod in such a position that the tripod head is about
level. This will make leveling the instrument easier.
Leveling The Instrument Using The Plate Vial
Loosen any two adjacent leveling screws until they are free but without
play. Rough level with the instrument in line with one pair of opposing
leveling screws. Learn and remember the rule: ** Thumbs in, thumbs out, the
bubble always follows the left thumb.” And always turn the screws in
opposite directions remembering that, the direction of movement of the
bubble is the same as the direction of movement of the left thumb. Maintain a
slight friction between the screws as they are turned. Repeat with the second
pair and then continue by alternating the adjustment with each pair of screws
until the bubble is centered in line with both. Make the final setting by
tightening just one screw of each pair so that the screws bear firmly (but not
tightly) on the footplate.
Leveling The Instrument Using
The Telescope Vial
Once the transit has been leveled using the plate vials, turn the instru-
ment to position the telescope level vial in line with two opposite leveling
screws, and center the bubble using the vertical clamp and tangent screws.
Then, turn the instrument (telescope) 180° and if the bubble does not center.
eliminate half the error with the vertical motion and the other half with the
leveling screws. Next, turn the instrument 90°, and center the bubble using
the leveling screws. The instrument should now be level.
Continue the procedure, alternating over each pair of opposite leveling
screws until the bubble stays centered in whatever direction the telescope
(and upper portion of instrument) are turned.
2. Dumpy Levels.
NOTE: In bright sun or on a hot day, allow the instrument to come to
temperature before attempting to ‘level up.
Level up by first releasing the tan- C
gent clamp and placing the telescope
in line with a pair of opposite leveling
screws (as A-B) and rotating them
while keeping them firm against the
foot plate, (Fig. 2)
Only two motions can be used.
Either both thumbs go toward each
other or both thumbs go away from
each other. The bubble will move in
the same direction as the left thumb.
When the bubble is brought to the
center, check that screws A and B are
still firm against the foot plate. Fig. 2
Watch that the level vial is on line over the screws being used. The
bubble will always move in the direction that the left thumb is moved. Keep
turning the pair of leveling screws until the bubble is approximately centered
in the level vial. Judge the position by noting the ends of the bubble. A
centered bubble will be between the two main graduations (longest lines) of
the level and will have each end equidistant from the main graduations.
Note, a bubble will change its length with changes in temperature, getting
longer when cold and shorter when warm. Consequently the reading of one
end against its adjacent graduations is not a satisfactory indication of center,
Get both ends of the bubble equidistant from the main graduations. And, itis
improper procedure to center the bubble exactly over one pair of leveling
screws without first bringing it nearly to center over the other pair of leveling
Now, rotate the telescope clockwise 90° so it is over screws C—D and
following the same procedure as for screws A—B, bring bubble to the center
making sure that the screws are still firm against the foot plate. Now turrí the
telescope counterclockwise 90° back to the first position, check the bubble
and recenter it if necessary. Finally, turn 90° clockwise to the second
position again and check the bubble, centering it again if necessary.
Your instrument is now leveled up, but one more check is necessary and
that is the adjustment of the bubble itself. Rotate the telescope end for end
(180%). The bubble should remain centered. If it doesn't, recheck the
leveling procedure. Then, if the problem persists, follow this adjustment
Note the amount of error in the bubble centering. With the pin wrench
supplied, turn the capstan screw at the right hand end of the bubble coun-
terclockwise if bubble is off-center to the left or clockwise if off-center to the
right. Turn this screw only enough to remove one-half of the error. Remove
the other half of the error with the leveling screws. Turn the unit end for end
(180°) and check whether the bubble remains centered. If there is still some
error remaining, again remove one-half of remaining error with the adjusting
screw and the remaining error with the leveling screws. At this point, 1t 1s
advisable to relevel with the other two leveling screws, so turn the unit only
90° (1/4 turn) and level up, centering the bubble only with the leveling
screws. Again turn the unit end for end (180%) and check for bubble
If adjustments were properly made, the bubble should remain centered in
all positions.
In any event, the adjusting procedure described above must be repeated
until the reversal test proves that the bubble will remain centered.
D. Setting Up The Optical Plummet Transit
Procedure For Set Up And Use
The Optical Plummet Transit:
a, features a magnifying optical system which can be focused from 18
inches to infinity;
b. employs an easy-to-view reticle with cross lines and target circle (bull's
eye) and
c. allows focusing on the ground point quickly by a simple motion of the
plummet eyepiece.
The Lateral Adjuster:
a, 1s affixed to the Shifting-Head tripod, is recommended for effective use
of the Optical Plummet;
b. allows almost 2 inches of travel in any direction and
c. affords the easiest and most accurate method of setting up over a point
regardless of wind conditions or type of terrain.
To Center Instrument Over A Point:
a. Set the instrument on the tripod and position it by eye as nearly as
possible over the ground point.
b. Level the instrument using the plate level vials.
с. If greater centering accuracy is desired, or if the instrument is more than
5 ft. (tripod height) from the ground point, also level the instrument with
the telescope level vial.
d. Focus the optical plummet reticle by grasping the smaller (uppermost)
knurled tube and slide in or out until bull's eye is in sharp focus.
To focus on ground point, grasp lower knurled tube and slide in or out
until ground point is in sharp focus.
Additional Suggestions:
If the ground point cannot be seen in the plummet field of view, loosen
lateral adjuster knob (located underneath the tripod head) one-half turn and
shift the instrument in the necessary direction.
If the tripod is offset to such a degree that the ground point cannot be seen
in the Optical Plummet, (1) reset the tripod as required, (2) relevel the
instrument, (3) shift the instrument while looking through the Optical
Plummet until centered over the point.
Until you get the feel of the Optical Plummet, or in case of peculiarities
of terrain, (1) attach plumb bob to hanger located under the lateral adjuster
clamping knob. (2) Adjust the instrument and tripod setup with the bob
suspended near the point until the bob is within approximately 3/4" of the
point. (3) Remove the plumb bob and push hanger out of the way. (4)
Proceed to center with the Optical Plummet as described above.
Although the Optical Plummet is designed to remain in adjustment
indefinitely under normal conditions, it should be checked occasionally.
Simply rotate the instrument (after leveling-up) while observing the point
through the Optical Plummet. If it stays on point the Optical Plummet is in
adjustment. If not, it should be adjusted by an instrument repair shop or by
the factory. Do not attempt to adjust it in the field.
E. Use Of The Transit With Beaman Stadia Arc
Berger Beaman Stadia Arc
When the stadia method of measuring distances is to be used to any
considerable extent, we recommend that Transits be equipped with the
special Berger type of Beaman Stadia Arc (See Fig. 3) This special auxiliary
graduation mounted on the Vertical Circle will be found to be a great
convenience in determining the vertical and horizontal components of in-
clined stadia readings. Instead of measuring the vertical angle in degrees and
referring to and converting the reading by means of the stadia tables, the
Beaman Stadia Arc makes it possible to dispense with these tables and to
obtain a similar result by a very simple calculation.
Assume an up-hill sight being
taken at an angle of approximately
10% degrees. By looking at the index
“Y” on the right side of the Vertical
Circle, it is noted that the correspond-
ing graduation on the circle is close to
|8. With the Telescope Tangent
Screw the inclination is changed until
the Index is exactly opposite the mark
|8. It is noted that in this position the
central cross wire intersects the rod at,
say 7.8 feet and that the stadia interval
on the rod is 6.4 feet. To obtain the
difference of elevation between the center of the instrument and the point on
the rod which is intersected by the central cross wire it 1s only necessary to
multiply the number opposite the Index Y” (18) by the stadia interval (6.4
feet) which in this case equals 115.2 feet. To obtain the elevation of the base
of the rod above the base of the instrument we need only add the height of the
instrument (say 4. 2 feet) and subtract the reading of the central cross wire on
the rod (7.8 feet); thus: — 115.2 plus 4,7 minus 7.8 equals 111.6 feet for
base to base elevation.
To obtain the horizontal component, the reading on the graduation
opposite *H 15 taken and used as a number by which the stadia interval 1s to
be multiplied, In the case above the reading would be 96,9, which, when
multiplied by the stadia interval 6.4, indicates a horizontal distance of 96,9
times 6.4 or 620.2 feet. If the conditions are such that only one of the stadia
wires in addition to the center cross wire can be read on the rod at one time,
the method can still be used by measuring the half interval and multiplying
the results by two.
F. Use Of The Stadia Reticle
In our transit telescopes the instrument constant need not ordinarily be
considered, since all stadia measurements give directly the distance from the
center of the instrument without having to apply the instrument constant (f
+ ¢), in other words, the stadia wire interval on the rod when multiphed by
100 will give the distance from the center of the instrument to the rod.
Strictly speaking, the constant multiplier (100) vanes according to the
distance. But the error involved in neglecting this small variation 1s much
less than the error of reading the stadia rod interval, Hence we are justified in
using the formula.
Distance = 100 5
s being the intercepted space on the rod between the stadia hairs.
G. Carrying Instruments
During field work ordinary transits and levels may be carried on their
tripods on the shoulder of the instrument-man. The tripod should be held in
such a position that the instrument is nearly balanced, but with a slight
tendency to fall forward when the tripod is held with one hand. In an
emergency the transit-man can bring his instrument quickly to a vertical
position and set it on the ground. When carrying an instrument through thick
woods or in passing through doorways it is advisable to put the tripod under
the arm with the instrument in front, so that the one carrying it is better able
to protect the instrument. For transportation in vehicles or whenever the
instrument would be in danger of injury if carried on its tripod it should either
be carried in its case or in the arms with one hand under the leveling base.
Obviously, there is less danger of damage and change to adjustments if the
instrument is in its case, because of its erect position and the protective
construction of the container.
When carrying the instrument on the shoulder it is best to clamp the
principal motions slightly to prevent wear on the centers, Clamp the transit
when the telescope is in line with the centers; the level when hanging down.
If this is not done and the instrument is allowed to swing, the centers will
gradually be worn oval and the instrument rendered unfit for good work. Do
not, however, clamp them so tightly that if the instrument receives an
accidental blow the clamps will not give, for this might result in a serious
injury which could be avoided by setting the clamps lightly. The leveling
screws should be brought to bear firmly on the footplate before the instru-
ment is lifted onto the shoulder.
H. Specific Parts of Transits And Levels, Use And Care
|. Telescope — Every surface of the lenses comprising the eyepiece
and the object glass should be free from grit and film to insure a clear image
in a telescope of high power. If the image appears to be foggy the lenses need
Dust may be removed with a fine camel’s-hair brush. To remove dirt film
from a lens, rinse it off in clean water and wash it with a liquid detergent.
Rinse the lens off and dry it as soon as possible. Do not allow the glass to air
dry. An old lint-free linen cloth should be used so that the lens will not be
When the telescope is being used the sunshade should be in place, to
prevent reflections. Furthermore the instrument is not perfectly balanced
without the sunshade. When the telescope is not in use the sunshade should
be replaced by the objective cap. In rain, place telescope vertical, object
end up, and no water can enter.
2. Cross-Hairs — If dust 1s allowed to settle on the cross-hairs they
will present a rough, irregular appearance.
To remove dust, unscrew both the objective lens and the eyepiece and
gently blow through the telescope tube. Before putting the lenses back into
place cover both ends of the tube with a cloth and wait a few minutes for the
moisture to evaporate. The objective lens should be screwed well against its
shoulder. Since the cross-hair adjustment may have been disturbed by the
removal of the objective lens this should be tested after the lenses are put
back into place. Do not unscrew the object glass unnecessarily for this is
likely to alter the collimation adjustment.
3. Transit Compass — The compass needle rests on a finely
sharpened pivot and the accuracy of the results obtained with the needle
depends more upon keeping the pivot point sharp than upon any other
condition. The needle should be let down as gently as possible onto its pivot.
When not in actual use it should always be raised by means of the lifter. If,
when lowering the needle, it is found that it swings violently to reach 1fs
North-and-South direction, check the movement with the lifter to prevent
undue wear on the pivot. When the instrument is being carried the needle
should, of course, be lifted against the glass cover.
The preservation of the magnetism is also an important factor in the
proper action of the needle. Magnets or iron or steel objects should not be
brought close to the needle on account of possible permanent injury. When
taking readings of the needle care should be taken that no ferrous substances
carried on the person are brought near enough to affect the direction of
the needle.
A silk, rayon, nylon or other synthetic cloth should not be used to clean
the glass cover of the compass box because of the likelihood of electrifying
the glass. After cleaning the glass breathing upon it tends to draw off the
electric charge. If the needle is attracted to the glass when a reading is being
taken, the cover may be touched with a moistened finger to draw oft the
When storing the instrument lower the needle and allow it to assume the
direction of the magnetic meridian; then raise the needle against the glass
cover by means of its lifter. When the instrument is sent from the factory the
needle is balanced for our latitude by means of a fine wire. When used in a
different latitude the position of the wire may have to be changed. If the
needle 1s only a little out of balance it is better not to disturb 1t. However, 1f
adjustment 1s necessary, raise the cover glass by first prying up (with a knife
blade) the circular split ring which holds it (applying the blade where the
ends of the ring meet), then lifting the glass by means of a piece of softened
beeswax. When the construction of the compass box 1s different from the one
just outlined, unscrew the knurled threaded bezel ring which holds the cover
zlass of the compass. The needle should then be raised by means of the lifter
and removed with a pair of tweezers. Move the wire countérpoise in the
direction required to balance it, replace it on the lifter, lower the glass and
then test the balance by letting the needle down gently onto the pivot.
Polara Transit Compass — The precautions noted pre-
viously apply also to the Polara Transit Compass. However, to operate the
compass on the Polara Transit, the operating instructions enumerated below
should be followed carefully:
|) To Release Compass Needle: Turn knurled pinion knob coun-
terclockwise (this releases locking thread). If needle should not fully release
after the knob snaps up, then again turn the knob slightly until the pinion can
be felt to engage the teeth in the variation ring.
2) To Dampen Free Swinging Needle: Push lightly downward on knurled
pinion knob,
3) To Lock Compass Needle: Push knurled pinion knob firmly down-
ward until it stops, then turn knob clockwise to engage locking thread.
4) To Set Declination: With needle in the released position — insert
adjusting pin in hole in knurled pinion knob and turn required number of
degrees from north index.
5} To Adjust Needle for Dip; Remove snap ring which holds cover glass.
Lift cover. (To do this easily, stick piece of cellophane tape on to glass and
pull up.) With housing in level position, rest needle on pivot. Both tips of
needle should stand at same height, If needle is dipped, slide coiled wire
counter-balance on needle toward high end. To re-assemble, lower cover
carefully into housing. Replace snap ring.
4. Graduations — Cleaning of the circles and verniers should
be kept to a minimum. When cleaning becomes absolutely necessary,
extreme care should be exercised to prevent damage to the edges and
graduations. Dust should be removed with a fine camels hair brush.
Rub the faces cautiously as wear on the edges will make it difficult to
obtain accurate readings.
To clean the graduations apply some fine watch oil and let it remain for
some time. Wrap a piece of old linen around a small, flat block of wood; hold
the block flat against the face and wipe gently. If this precaution is followed
the danger of breaking down the edge will be minimized.
The inner edges of the circles and verniers should be free from dirt and
grease before replacing the inner center. The verniers must not be removed
from the upper plate nor the centering of the circle altered, as their adjust-
ment is too delicate for anyone but a qualified instrument repair man.
Both the glass vernier covers and the compass cover should be carefully
brushed and cleaned. If the shades become dirty they should be taken from
their frames and washed in soap and water,
5. Centers — The centers should revolve freely but without the
slightest looseness. If they do not turn easily they should be cleaned as soon
as possible. To do this unscrew the knurled nuts on both the plate and lower
clamp tangent housings. This will release the spring pressure on the pistons
and will facilitate the disassembly and reassembly of the instrument. Then
remove the cylindrical cup which carries the plumb line chain and hook.
Now unscrew the retainer nut attached to the inner center using wrench
supplied with the instrument, and gently raise the vernier plate from the
lower part of the instrument. Then remove the horizontal circle and the outer
center assembly.
To clean the centers. use a turned stick which has approximately the
same taper as the centers. Cover the stick with a lint free cloth or a piece of
chamois on which a small amount of watch oil has been applied and clean the
sockets carefully. Replace the cloth or chamois with a fresh piece without oil
and repeat this procedure. Apply a small amount of watch oil to the surfaces
and reassemble the instrument.
After the cleaning has been completed it 15 advisable to check the
performance of the centers. Level the instrument. While holding the vernier
plate stationary slowly revolve the horizontal circle about 30° at each turn
until approximately six positions have been checked. Be sure to examine the
telescope bubble after each turn to see if it has maintained its level position.
If it does not, the condition of the centers must be checked as they may
require refitting.
6. Level Vials — The level vials used on Berger Engineering
instruments are carefully ground on the inner surface to a curvature suitable
for the particular purpose for which the level is intended. The glass tube is
filled with a fluid which responds quickly to any change in inclination.
Level vials are very susceptible to the least change in temperature, as will
be noticed by the changes in length in varying termperatures during field
work. One of the greatest sources of error in the use of level vials is that due
to unequal heating of the level tube. This is particularly noticeable with
higher precision/lower sensitivity vials. Whenever there is unequal heating,
the bubble tends to move toward the warmer end. This is due more to a
change in the condition of the liquid itself than to any change in the form of
the glass tube. Therefore it 1s very important to protect the level as well as
possible from all sources of heat, not only from the direct heat of the sun but
from the heat from the hands or the breath. In using very sensitive levels it is
important that no part of the body should remain near the level long enough
to affect it. If a level has been improperly exposed and is therefore liable to
error it should be covered with a cloth for a few minutes until the termpera-
ture has become uniform.
7. Leveling Screws — The screw threads of leveling or
tangent screws should be kept clean to avoid sticking. For this purpose use a
stiff tooth brush dipped in a solvent such as gasoline. Then apply a thin film
of lubricant,
8. Tripod — The tripod legs should not be allowed to become
loose. The wing nuts and bolts at the head of the tripod should be well
tightened up. If one of the tripod legs is raised and allowed to fall of its own
weight it should sink slowly to the ground. If it drops quickly itis too loose; if
it does not fall it is too tight, The shoes should be examined to see if they are
loose. The screws should be set up tightly. The points of the shoes should be
sharpened whenever necessary. Wooden tripods should be kept well var-
nished to preserve the wood from the effect of moisture, and should be wiped
off, 1f wet. Metal tripods should be wiped with a cloth to prevent damage
from moisture and sprayed with a rust corrosion preventative.
9. Carrying Case — The safety of the instrument often de-
pends upon the way it is packed in its case. With a wooden carrying case, 1f
any of the wooden blocks should become loose they should be repaired at
once; the rubber cushions underneath the box, the leather straps, buckles,
hinges and locks should be examined frequently and kept in good condition.
The case should be vamished whenever necessary. If it becomes wet, it should
be wiped dry. If a plastic case is provided, wipe dry and keep clean.
A. Repair Shop Adjustments
The following adjustments should not be attempted in the field and
must be made only by a qualified repair service center or by the factory:
The fitting of centers.
The centering of the graduated circles and the verniers.
The fitting of focusing slides.
Straightening and re-magnetizing needle, and straightening and
sharpening pivot,
B. Adjustments Of The Transit Which Can Be Made
In The Field And With Which The User Of The
Instrument Should Be Familiar
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|. Adjustment of the two plate levels.
2. Adjustment of the cross-hairs:
(a) Adjusting the vertical cross-hair.
(b) Adjusting the cross-hairs into the line of collimation.
3. Adjusting the horizontal axis.
4. Adjusting the telescope level.
5. Adjusting the vernier of the vertical arc.
|. Plate Levels — To adjust the two small plate levels
so that their axes are in planes at right angles to the vertical axis of the transit,
turn the plate until each level is parallel to the line through a pair of opposite
leveling screws, center each bubble carefully with the leveling screws and then
turn the upper plate 180° in azimuth, that is, until each bubble has been
turned end for end. Any displacement of the bubble represents twice the
actual error of adjustment. To correct this error move the capstan-head
screws on the level cases so as to bring each bubble halfway back to the
center. Then re-level by means of the leveling screws and test the adjustment
again. Several repetitions of the adjustment may be required. When the
levels are in perfect adjustment they should remain in the center in all
azimuths. (See Fig. 4 — Fig. 7).
The function of these levels is to place the vertical axis in a true vertical
line. Whenever this must be done with great accuracy it is always possible to
use, for this purpose, the long level attached to the telescope. This level is
more sensitive than the plate levels and gives a better control over the vertical
axis. By centering the bubble over one pair of leveling screws, turning 180°
in azimuth. and correcting half the displacement with the tangent screw on
the standard. and the other half with the leveling screws, the level axis and
the vertical axis are placed at right angles to each other. This test should be
repeated several times over each pair of leveling screws. When the bubble
will remain central in all azimuths the axis is vertical.
Plate Bubbles on some Astron and Polara transits employ the same
principle of adjustment as described in the preceding under ‘’Platé Bub-
bles. ‘* However, these transits have plate bubble mountings, spring loaded
on one end.
To adjust bubble, insert adjusting pin in capstan screw located under
bubble housing and rotate in direction required to bring bubble toward
center, A clockwise rotation lowers this end of the bubble — coun-
terclockwise rotation raises it.
Caution — Do not rotate this screw in counterclockwise direction be-
yond that necessary to center bubble. If it is forced too far the spring loaded
mounting will be distorted and the spring action will cease to be effective.
This will result in unstable bubble action.
2. Cross-Hairs — In a perfectly adjusted instrument the
intersection of the cross-hairs should lie in the optical axis of the telescope,
the vertical hair should lie in a plane perpendicular to the horizontal axis of
the transit, and the line of sight as defined by the vertical hair should be
perpendicular to the horizontal axis, (See Fig. 8).
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Bubble Adjusted Transit Re-leveled
To test the vertical hair sight on some distinct point, with the plates
clamped but the vertical motion free. Be sure that the eyepiece is adjusted so
that there is no parallax. Now slowly raise and then lower the telescope. The
vertical hair should remain exactly on the point as it moves across the field of
view, If the cross-hair does not remain on the point, loosen the capstan-head
screws holding the diaphragm and, by tapping lightly, rotate the ring until
the cross-hair is in such a position that it will stand this test. Tighten the
screws sufficiently to prevent the diaphragm from moving out of place.
Fig. 8. Test for Verticality of Cross-Hair
To place the cross-hairs in the optical axis proceed as follows: — Move
the cross-hairs so that they appear to be centered in the field of view. This
assumes that the eyepiece tube was properly centered when it left the shop
and that it has not been disturbed since.
3. Collimation — To adjust the vertical hair so that the line
of sight is perpendicular to the horizontal axis try prolonging a straight line,
first with the telescope normal then with the telescope inverted.
~—Transit Center
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1 A
Fig. 9. Test of Line of Collimation
[f the results agree, the adjustment is correct. Set up the transit (Fig. 9) at
E and sight on point A with the vertical hair and clamp the plates. Reverse
(plunge) the telescope and set point B in line with the vertical hair, and
presumably in line with AE prolonged. Turn the telescope about the vertical
axis until the vertical hair again sights A and clamp the plates. Invert
(plunge) the telescope and see if B is again sighted. If not, then set point C in
line with the vertical hair, alongside of B. The position of the vertical hair is
in error by one-fourth the distance from C to B. To adjust, loosen the
capstan-head screw at one side of the diaphragm and tighten the opposite
screw until the vertical hair has apparently moved one quarter away from C
toward B, that is, to point D.
4. Erecting Telescope — NOTE — Since the telescope
shows objects right-side-up the image of the cross-hairs is really inverted; so
we must move the cross-hair in the opposite direction from that in which it
appears that it should be moved. If the cross-hair is to the right of the true
point, then the diaphragm should be moved to the right (by loosening the
screw on the left and tightening the screw on the right), when the vertical hair
will be seen to have moved (apparently) to the left.
The test for error of collimation should be repeated several times if
necessary, and the diaphragm adjusted, in order to be sure that it is correct
and that no movement of the tripod has affected the result.
>. Horizontal Axis — To adjust the horizontal axis so that
it 1s perpendicular to the vertical axis, sight the vertical hair on a high point,
such as a point on a tall building not too far away (the vertical angle should be
at least 305), clamp the plates, then lower the telescope (about horizontal
axis) and set a point, or note the position of some point directly in line with
the vertical hair and apparently vertically beneath the high point. Next
reverse the telescope on its horizontal axis, turn it about its vertical axis, and
sight the high point again, and clamp the plates. Lower the telescope and see
If the vertical hair is again on the point previously set. If not, set a point in
line with the vertical hair. Now mark a point midway between these two. The
adjustment is made by raising or lowering the adjustable end of the standard
until the vertical hair will travel from the high point to the midway (low)
pont in either position of the telescope. It is important that the instrument
should not be disturbed between the two tests, and of course the leveling
screws should not be touched.
If the adjustable end of the axis must be raised, loosen the axis friction
screw on top of the cap, move the adjusting screw controlling the adjustable
block, by first releasing the lower nut then tightening the upper one, then
re-tighten the axis fiction screw on top of the cap, If the adjustable block
must be lowered, adjust the block by loosening the upper nut and tightening
the lower one. Then re-tighten the axis friction screw on top of the cap. The
opposing nuts should be brought to a firm even bearing, and the cap screw
should be tight enough to give the proper amount of friction on the horizon-
tal axis. When this adjustment is once properly made it rarely has to be
6. Telescope Level — The long level vial attached to the
telescope should be adjusted so that the bubble is central when the line of
sight is horizontal. This may be done by setting up the transit midway (by
measurement) between two stakes or other points which may be used as
bench marks. If it is possible to drive the two stakes so that their tops are at
exactly the same elevation, as shown by readings of a rod held on top of the
stake, this will make the calculation simpler; but 11 you cannot, any two
points may be used. The difference of elevation of the two points is given
correctly even if the adjustment is in error, because the instrument is equally
distant from the two points. (See Fig. 10).
Next move the transit to a point (outside) in line with the two stakes, but
much nearer to one than to the other. Take rod readings on both stakes. If the
two readings agree the adjustment is correct; if they do not agree elevate or
depress the telescope until the reading on the distant stake is the same as the
reading just found on the nearer stake. Test again on the near stake; if a
different reading is obtained re-set on the distant rod, and continue this
process until the two readings agree. Then, keeping the honzontal hair on this
last reading on the distant mod, move the level, by means of the capstan-head
nuts, until the bubble 1s central.
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Fig. 10. Testing the Telescope Level
If, instead of using two stakes set at the same elevation, the test 1s made
on two bench marks whose elevations differ, say 1.030 ft., it is necessary to
allow for this difference when comparing the near and distant rod readings.
If this is done the final result is the same as when sighting at points which are
at equal elevations; that is, the line of sight 1s honzontal when the two
readings differ by 1.030 ft.
7. Vertical Arc — To adjust the verniers of the vertical arc
(or circle) to read zero when the telescope bubble is central, level the
instrument first by means of the plate levels, then by means of the telescope
level. Set the vernier so that it reads very nearly zero, which can be easily
done within 14" or 14'. Next adjust the distance between the vernier and arc
so that when the zeros coincide the 30' lines, nghtand left, also coincide. To
do this, set the zeros exactly together by means of the vertical tangent screw;
then by moving the vernier inward a little, if the 30" lines fall short, or
outward if the vernier space is too long, this adjustment is perfected. To
make the final adjustment loosen slightly the screws holding the vertical arc
to the horizontal axis, center the bubble carefully, and then tap one of the
spokes very lightly until the zeros coincide exactly. Set up the screws on the
vertical arc, and repeat the test to see if the vernier reads zero when the
bubble 1s central.
8. Vertical Circle — If the transit has a vertical circle
with vernier at eye end, or with opposite verniers, the adjustment 1s to be
made with the milled capstan-head screw attached to the vernier frame at the
side of the standard. First level the instrument so that the telescope bubble
and the plate bubbles will remain central when the telescope 1s turned in
azimuth. The zero of the vernier is then adjusted to read zero on the circle by
turning the milled-head adjusting screw (using an adjusting pin} until the
zeros coincide. The adjusting screw is then held in position by tightening the
small binding screw.
Y. Vernier Level — If the vernier of the vertical circle has
a control level attached to its frame the adjustment of this bubble is made as
follows: — place the line of sight in a horizontal plane by means of the
telescope tangent screw, then move the vernier frame tangent screw until the
zero line of the double verniers, marked A, is in coincidence with the zero
line of the vertical circle. Now raise or lower the adjusting screw of the
vernier level until the bubble 15 in the center of its tube.
10. Interchangeable Auxiliary Telescope — If the
transit 1s equipped with an interchangeable auxiliary telescope it can be
adjusted as follows: The intersection of the cross-hairs should be placed in
the optical axis of the telescope. Since we place the lenses so that the optical
axis coincides with the axis of bore of the tube, the cross-hairs may be placed
in the optical axis by rotating the telescope in improvised wyes. Such wyes
may be cut of thin wood to the proper shape and size and securely fastened.
The distance between them should be such that the telescope may rest upon
the collar outside the object glass and upon the tube near the cross-hairs. The
adjustment 1s then made by first noting where the cross-hairs are pointing,
then rotating the telescope 180" about its own axis in the wyes, then moving
each hair halfway back to the point it first sighted, using the capstan-head
screws of the diaphragm for this purpose.
To adjust the auxiliary as a top telescope, sight the vertical hair of the
main telescope at some distant object and clamp the horizontal motion.
Release the small nickel-silver capstan-head screw at the opposite side of the
clamp having the two tangent screws. Twist the auxiliary telescope around
so that itis nearly parallel with the main telescope. Then tighten up the nickel
capstan-head screw again. Sight the vertical hair of the top telescope on the
same distant object, using the opposing milled-head screws for this adjust-
The position of the horizontal hair is really unimportant so long as the
telescope is used only for measuring horizontal angles. If it is used for
vertical angles when mounted on top it becomes important to make the line
of sight parallel to the line of sight of the principal telescope. To make this
adjustment, sight the horizontal hair of the main telescope at some point.
Measure off above this point the distance between the two telescopes and
mark a second point. Then move the diaphragm until the horizontal hair of
the auxiliary telescope sights the second point.
To adjust the auxiliary as a side telescope, sight the horizontal hair of the
main telescope at some distant object and clamp the vertical motion. Release
the smaller nickel-silver capstan-head screw, twist the auxiliary telescope
until nearly parallel with the main telescope, then tighten the nickel
capstan-head screw. Then sight the horizontal hair of the auxiliary telescope
at the same distant object, using the milled-head opposing screws for this
[f the side telescope is to be used for measuring horizontal angles the
vertical hair may be adjusted by sighting the main telescope at an object, and
measuring off the distance between the telescopes, right or left, to establish a
parallel line. The vertical hair must then be moved by means of the capstan-
head screws of the diaphragm until it sights this last point.
11. The Level — To adjust the level tube we must place its
axis in the same vertical plane with the axis of the collars and also make it
parallel to the axis of the collars. Since an error in either of these conditions
affects the test for the other we should not consider either one complete
before the other has been tested. First test the parallelism by rotating the
telescope (if necessary) so that the level is exactly beneath it; center the
bubble, then carefully lift the telescope out of the wyes, turn it end for end
and carefully replace it in the wyes, the object end now being where the eye
end was at first. If the bubble reads the same the adjustment 1s correct. If 1t
does not the bubble should be brought halfway back to its original (central)
position by means of the two nuts controlling the vertical adjustment of one
end of the level tube.
Next test the bubble to see if it is in the same plane as the axis of the
collars; this is done by rotating the telescope about its own axis some 15° or
20° from its normal position, first one side, then the other. The bubble will
always move toward the higher end. To correct any error observed, move the
capstan-head screws controlling the horizontal adjustment, moving them in
such a way as either to lower the higher end or to raise the lower end.
C. Adjustments Of The Dumpy Level Which Can Be
Made In The Field
a. Adjustment of the Level
Making the level axis perpendicular to the vertical axis.
b. Adjustment of the Cross-hairs
(1) Placing the horizontal hair in a plane perpendicular to the
vertical axis.
(2) Making the line of sight parallel to the level axis.
|. The Level — The level of the dumpy must first be made
perpendicular to the vertical axis of the instrument. This is done by centering
the bubble with the leveling screws, reversing the telescope end for end
about the vertical axis, and noting the position of the bubble. (Fig. 11 a,b.) If
it has moved out of center bring it halfway back by means of the vertical
adjusting screw (at the eyepiece end). The test and adjustment should be
repeated until the bubble will remain central during a revolution of the
telescope in azimuth.
2. The Horizontal Cross-hair — First test the horizontal
hair to see if it will remain on a point as the telescope is moved right and left
about the vertical axis. If it will not, the diaphragm should be rotated until it
will stand this test. Loosen the screws holding the cross-hair ring and tap
gently on the screws until the horizontal hair is in such a position that it will
remain on the same point as the telescope is moved in azimuth. (See Fig. 12).
Cy — 2
3. The “Peg” Adjustment — To test the line of sight to see if
it is parallel to the axis of the level two stakes or two marks may be set at the
same elevation about 200 or 300 feet apart. This may be done with the level
itself by placing 1t accurately midway between the stakes. If the bubble 1s
centered carefully and the stakes driven or the marks set so that they are at the
Fig, lla. Test of Bubble of Dumpy Level (bubble centered)
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Fig. 11b. Test of Bubble of Dumpy Level (telescope reversed)
same elevation as shown by a rod reading, the points will actually have the
same elevation, even though there is a large error in the adjustment of the
instrument. Now set the level in line with the stakes and near to one of them.
Next center the bubble and take rod readings on the two stakes. If the
readings do not agree raise or lower the cross-hair ring until they do agree,
This is done by moving the diaphragm until the reading on the distant rod
agrees with near rod reading just found, This adjustment, however, will alter
the near rod reading slightly, so the readings and the adjustment must be
repeated, until finally they are made to agree. (See Fig. 10.)
Fig. 12. Test of Horizontal Cross-hair of Dumpy Level
4. Second Method — It is not really necessary to set stakes at
the same elevation. Any two bench marks may be used for testing the level,
provided they can be read trom the same set-up of the instrument. Set the
level close to one of them so that the eyepiece 1s within about an eighth of an
inch from the scale on the rod. Take a reading (say 4.00 feet) on the rod by
looking through the object end of the telescope. Next move the rod to the
distant bench mark and take another reading (say 5.90), the bubble being in
the center. The difference of elevation is apparently 1.90. Now move the
level to the other bench mark and repeat the operation. Suppose that the near
reading is 3.80 and the distant reading is 1.70. The difference in elevation is
in this case apparently 2.10. The true difference in elevation 1s, there-
fore, the mean, or 2.00 feet. Since the line of sight of the telescope 15
now 3.80 above the bench mark the cross-hair should read 1.80 on the
distant rod. Since it actually is at 1.70 the line of sight 1s 0.10 toot too
low. The diaphragm must, therefore, be so moved that the horizontal
hair will read 1.80 when the bubble 15 central.
Models 474 and 484
Dumpy level with horizontal circle and vernier. (Available without horizon-
tal circle and vernier as Models 472 and 474). 33-power erecting, internal
rack and pinion focusing telescope. 1.535" diameter achromatic objective
lens. Clear aperture: 1.50" ,816ft. short focus. Focusing type eyepiece,
Forged brass bar and skirt. 3-7/16"" diameter horizontal circle with double
vernier reads to 5 minutes (1/12°). Dust protected micrometer clamp and
tangent screws. 734°" precision ground telescope level vial - sensitivity, 50
secs, per 2 mm div. 4 nickel silver dust protected leveling screws. Forged
brass foot plate with government standard 3-1/2"" x 8 thd. Forged shifting
center for setting over a point. Carrying case, sunshade, pin wrench, plumb
bob and instruction Manual. Metal wide frame stiff or extension tripod
available. Also available with Power Zoom System.” Range: 28 to 44
power, Models 474 and 484 used with #873 and 874 tripods. Model 472 and
482 used with #893 and 894 tripods.
“Optional, extra.
The following drawings are included as an aid for use when ordering
parts. Although the drawings are of older models, the parts numbers shown
are generic and apply to similar parts utilized in instruments of current
manufacture. When ordering please specify the appropriate part
number and the serial number of the instrument for which the part is
[9497] Adung suma your ST 198199 dy) 107 SJIEQ iw Basreior = + or
Fo тыат ео Обр E = В |
Ar Beye? = — E MADE Sy [E
Dejas" a a TÉ
Éd sde 3 Ltr Bun PES
DATA TUI AD ICE pu ¿Pay ¡DIA PE mao Duce a. E
ip Fr Par DEL LAN NE
md | ‘
o py Bay
2 E
209 J pr
FO ur м
$ ; cimas
| Tricscore Crass
| Ears Liar —
173 Tobeacapa Ciomp Pegar N
fod "Cosa Toe | ла
| 795 + m Screw
| 196 = Tangent Jerew
ivr = * Take-ups Screw
#30 wReobeeolle Bushing
109 + Bug AÆAutening Serew
fa 08 rue “A' Standard
202 wm e es with Adjustable
TEL EEE "cano 20% = = Aut Wye Bearing
204 + # arent Sid
Telescope Clamp | BES = a A nn
| 208 = = Moser
| Aessmaue Wie Beagies
то Easy
207 Adjustable Wie Bearing & Stud
cu “ a Nr
209 We Bearing Felt Qrer
ord " Cop
LE 275 STF Lhd
a Г] E EE
Ч :
o E El E ES,
Aa WIL E 27 asa
= A |
CL 4.
A,—Cross Section of Erecting Transit Telescope
В, — Cross Section of Inverting Transit Telescope at eye end
Include instrument serial number when ordering parts
Th TEL Soa ET Tes 9
242 scone Oud Coo EE Peces Jicrm Er eg BIE Leve Cp 267 Eyemece Dust Cap
hy “Her Jim rd “ Loves, Loci ее ния Sor 2 Ч a
Cir Ces Frec æ EY F “rase
|<#5 Pesca An ed er EJ + = + Je 270 Ada
Ed > Bar Lio SEE ow do 240 Ticos jas E dorama uo
| Йо ee LN AECA A LS + E. oia ,
Cr — A CE EFT ds “а ip APN ET “ber
LFF nm 7h her Er vos Heong EF н re SP abe a A ED Eu FRA ter
a = jor E wm JA DEF Ta sooné, Jneriens EE as = Serer
жом m= Dore ео = = Leip у" оба буден етот EE “oa Ne
DO el, Frecimg ré e Atar Ary LOS 27 em ue
FIT vw Seem V5 € = Jere — O arias Dave $ Ferew EE edie SC 300 L&T aeacripe
19 Tripod L P f В ME Enga sr |
Te arts tor Berger lransits [i e dr |
ra | dd; "я n=
por = “Loot Тела! (ds = = Aston
- Me» = Bore
Fo Pi Mecs F350 " + eh
E Pam Bog Бы ON Cas FX? Morirpetal Herne
E a E CA E A FI Papua Cor Dias
RE Foot Blade Кун e "ae
WO Sif fing Flore Era + bee
FT Ball Nor 1 a м а TR Tr
A Lock Ica AE + " бля
ES Carter A Ея 137 Compora kv" y
sea a rg | 133 Core o
m PA JAF Héroe
HE mm Dusk Cap Lr MOS “+ Bel
e E Meri dor ‘А 8 = A
Face | ie" Neagle Laer Fous
E in "E Ea ён hating "ÉS 1 lr z
ci " Doing Cy (64 Seréw
я Be por Cr | ny = Mao
ños на AE | | 88 Voraton Brian
re e E. ei AT
e: sa fa a e A: ¡50 o Pata Level
m ira Гир A =» = = Fra
Ed # # Jere #79 “ = Serew
er 8 ong Jere MF HAD PEP mw slain Mud
joa MO“ SE war | HD = = 5 Apart
я ea Data d FAA ui " Guo
Berrie ee ri VN El | 774 Séance Crrcie Side
| A a ré Fp ry я Cas dk e г Srl dg
A br“ Г т Je
5 kw av CP a Fai "a oe Fait Г
44 for Center : (70e e Mol
35 ow « Æ AE
138 Porientar Gral | er 17/80 m Adhusting Krew
#37 1" Ne к MaS ea |
L "15 a = Es Soran |
3 ré Center Sow fad Wer cal Fermer |
Eds Flore (qd = = Screw |
£ Е Тамар PL has | КВ 6 Compe
- ri ¡Els "FPE 4 de РЕ =. Jr
| crew
| Pate Tengent Form VF à = Guard
Er я = LE Pere | ая if i ni en
i Pr
¡A pre ang 149 Telescope
dé fr. Maid
NO des Au AA
———]Ñ <————]——]]—. К
Wm Gm Ч И ta =
Lower Citan
Vernier Plate Clamp (For Horizontal Circle)
Cross Section of the Berger “R”” Transit with Yoke Frame and
Include instrument serial number when ordering parts
Vertical Circle Parts for Berger Transits
Plain Vertical Circle
(à 28028
Beaman Stadia Arc
(With Indices)
e Far IE Sa
- = - LOTE
Beaman Stadia Circle
(Double Opposite Indices)
Bara. La
A Pe +A
1784 = = Res
| 257 Mr agar Meta
| 25 Aros CA Care
a = CA
olf = Райт
dér = Fee Ce
E a ofr wp Swe
#42 = = JA
Po + = быт
der = = y
dur + = = Cp
Include instrument serial number when ordering parts
V Packing and Packaging for Shipment
Parts and/or instruments and accessories shipped to the factory for a
repair estimate must be carefully packed and packaged to minimize damage
in transit. Securely fasten all motions, properly position the instrument
within its case, and cushion it with tightly rolled newspaper wads, foam or
other packing material of suitable protective density, Then, securely fasten
the case and place 1t in a well fitting cardboard carton (minimum test 200
Ibs.) or wooden box, cushioning around the case where needed. Close the
package securely, using adequate tape, staples, nails, etc, . . . and address
the repair and all correspondence pertaining to it to:
Repair Dept.
4 River St.
Boston, MA 02126
It requested, an estimate as to nature, duration and cost of repairs
required will be furnished to you at no charge soon after vour instrument is
Note, unless approved, incoming goods will not be accepted on a freight
collect basis and in all cases all freight charges will be borne bv the customer
making the return.
VI Berger Reticles, Leveling Rods And Tripods
Berger Reticles
Spider web or ruled on optical glass — are available in any pattern or
style required. Reticles regularly furnished in Berger instruments have line
widths of .00013" to .0002" according to U.S. Government standards. Line
widths ranging from .0001” to .0015” are available. A few of the many
possible variations are shown: here,
21 27 32 36 38 43 a7
Berger Circle And Vernier Graduations
Hustrated below are the most frequently used graduations on circles and
verniers. The inner row reads 0°-360° clockwise: the outer row 360°-0°
Circle graduated to 30 minutes. Circle graduated to 15 minutes.
Verniers read directly to one minute. Vermers read directly to 20 seconds.
Circle graduated lo 20 minutes, Circle graduated to 10 minutes.
Verniers read directly lo 30 seconds. Verniers read directly lo 10 seconds,
counter-clockwise. Figures are inclined in the direction they should read.
Other types of graduations and numbering methods are available. A diagram
showing the stvle desired should be sent with the order.
Berger Leveling Rods And Targets . . . . Deluxe Series
Built to take hard usage. Solid maple construction. Walnut finish with
protective clear lacquer, Integral painted face has sharp black lines and
highly legible numbers deeply engraved on white background. Foot num-
bers painted International Orange for ready identification. Metal foot shoe.
Positive clamps with large, easy-to-handle knobs.
Unique, snap-on vernier target with quartered oval, alternately white and
International Orange. Vernier reads to 1/64" on builders’ rods and to 1/1000
ft. on engineers’ rods.
rayegerge repre ej
y e A с;
— &
í >
к Ë =
Builders’ Models Es
(Graduated in feet, inches and eighths) я
#62 2 section, 8 ft. clamping — cast oval target =
#87 2 section, 10 ft. sliding, 5% ft. closed, snap on target Ea
#86 3 section, 15 ft. sliding, 5% ft. closed, snap on target Е
Engineers Models Я
(Graduated in feet, tenths and hundreths) | »
#77 2 section, 10 ft. sliding, 5.6" closed, snap on target 0 Е
#76 3 section, 15 ft. sliding, 5.6" closed, snap on target En
Metric Model
(One centimeter blocks, 5 centimeter lines, numbered each decimeter in
black. Meter graduations in-red.)
#96 2 section, 3.35 meters, sliding, 1.75 m closed, target fumished
Berger Leveling Rods And Targets . . . . Custom Series
Heavy-duty professional rods for surveyors and engineers. Straight
grained hard maple carefully selected and well seasoned to resist tough field
use and to maintain straightness. Stained dark for protection and marked
contrast with face. Conventional integral painted face rods and rods with
replaceable white-steel faces are available. Faces recessed for protection;
graduations are bold, sharp and well defined: easily operated, durable
fittings. Foot numbers in red for added legibility.
Vernier targets in alternating red and white quadrants read to 1/1000 of a
Engineer's Models
(Graduated in feet, tenths and hundredths)
#79 3 section, 12"sliding, Frisco Rod only, 4'-6" closed. Direct reading.
Replaceable metal scales.
#75 > section, 13’ sliding, Philadelphia Rod, 7' closed. Replaceable
metal scales. Manual head block adjustment. Vernier target.
#74 Same as No. 75 Rod. Micrometer target.
#73 3d.section, 12’ sliding, Frisco Rod only, 4'-6" closed.
#72 2 section, 13" sliding, Philadelphia Rod, 7’ closed. Vernier target.
#71 2 section, 13" sliding, Philadelphia Rod, 7' closed. Specially
mounted steel scales. Dimensional changes in wooden portions have
no effect. Vernier target.
#70 Same as No. 71 Rod. Micrometer target.
Berger Standard Wide Frame Tripods For
Engineers Instruments (Models 843, 844,
845, 846, 849 and 850)
Solid maple or other suitable hardwood legs and reinforcing blocks. Cast
aluminum shoes with oversized push down spurs. Finished in yellow and
white with black highlights. Complete with strap, protective cap for threads,
and tension-adjusting wrench. Models available: U.S. Standard 314" x 8
thread tripod head (#843 stiff — #844 extension). European type flat-top
head with 36" x 11 thread instrument fastener (#849 stiff — #850 exten-
sion). Special Berger Lateral Adjuster shifting head with 314°" x 8 thread
mounting (#845 stiff — #846 extension). Latter is required for conven-
tional 4 screw optical plummet transits; is Teflon™* coated for smooth
sliding action and permits approximately a two inch shift in any direction of
the transit while centering over the point. Stiff leg tripod is 60" long.
Extension tripod is 38” closed and extends to 61."
Reg. TM of DuPont
Berger Standard Tripods For Use With Engineers
Transits And Levels (Model 841 — Stiif Leg:
Model 842 — Extension Leg)
U.S. Standard 314 x 8 thread head. Kiln-dried, straight grained ash or
other suitable hardwood, painted yellow and white. Cast aluminum shoes
with exceptionally strong points. Extension leg tripods have angled points to
position them vertically during normal set-up and are keyed to prevent
rotation. Two heavy clamps with forged brass shoes assure positive clamp-
ing and long wear. Rugged spreader ring for extra rigidity. Furnished with
strap and protective cap for threads. Heavy shoes with push down spurs and
replaceable steel points. Stiff leg tripod is 58" long. Extension leg type 1s 37°
closed and extends to 39”,
Berger Light Wood Tripods For
Engineering Instruments
(Model 821 Stiff Leg; Model 822 Extension Leg)
Kiln dried, straight grained hardwood painted yellow and white for high
visibility, Cast aluminum shoes with push down spurs, durable steel points.
U.S. Standard 314" x 8 thread head. Extension legs have angled points.
Tested, rugged clamps. Complete with strap and protective cap. Stiff leg
tripod approximately 58” long. Extension leg type 1s 59" collapsing to 37,
Berger Meial Wide Frame Tripods =
(Models 873 and 893 — Stiff Leg;
Models 874 and 894 Extension Leg)
Rugged, lightweight and easy to handle. Wide frame design lessens
torque and increases stability. Cast aluminum shoes with sizeable foot spurs
and angled points. Finished in yellow and white with contrasting black
accents for on-site safety. U.S. standard 34 x 8 thread head. Furnished
complete with strap and protective cap for 3' x 8 threads. Heavy shoes with
large push down spurs and steel points. Stiff leg models are 58°" long.
Extension leg models use hard wood center sticks and extend from 37°" to
59°". Lightweight steel legs furnished as standard on all models. Aluminum
legs available on special order at additional cost.
Also available with flat top head utilizing 5/8 x 11 fastening system as
model 893 (stiff leg) and 894 (extension leg).
Berger Instruments
(617) 298-0170 |
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