THE SPINDLE STAGE: A MODIFICATION UTILIZING A

THE SPINDLE STAGE: A MODIFICATION UTILIZING A
THE AMERICAN
THE SPINDLE
MINERALOGIST,
VOL. 47, JULY-AUGUST,1962
STAGE: A MODIFICATION
HYPODERMIC SYRINGE
UTILIZING
A
M. J. OeraNranrrn,Department oJ Geology,Hebrew Uniaersity,
Jerusolem, Israel.
ABSTRACT
A new spindle stage is described built around a hypodermic syringe. Advantages of the
simple design include rigidity coupled with smoothness of rotation.
INrnonucrrow
The use of the spindle stage is now well establishedin mineralogical
practice. The diverse designsdescribed,together with a generalaccount
of their operation,have been summarizedby Wilcox (1959).A new form
of stage is described hereunder which is simple in its construction yet
robust, convenient to use, and capable of yielding results of acceptable
accuracy.
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A mounted stage is shown in Fig. 1. It consistsof three assemblies.
There is firstly the hypodermic syringe to which the measuring pointer
and protractor are attached with the aid of rubber tubes. Secondly,there
is the glasscell, in which the immersion liquid is held; several cells'may be
prepared for each stage. The cell is an independent unit which can be removed completelyfrom the stage;it has a channelsawn into one side for
introduction of the needle-mounted grain. Thirdly, there is a wooden
base plate on which the syringe is held, and to which the glass cell is
clamped by the ordinary microscope clips; the base plate is screwed
onto the rotating stageof the microscope.
A dismantledstagecan be seenin Fig. 2. The syringe assemblyis held
on the base-plate by the rivetted strip of plastic tubing; whereas the
entire syringe can be moved forcibly-during initial assembly and for
purposes of centering-it remains stable while the plunger is rotated.
Apart from the addition of rubber tubing for holding the measuring
devices, the only modifi.cation of the syringe which is necessaryis that
the tip of the plunger be sawn off; a small amount of cork is stuffed into
the hollow thereby exposed.The needle on which the mineral grain is to
be mounted will be stuck, pointed end first, into this cork. The mineral
may therefore be rotated by turning the plunger head while the syringe
housing is clamped to its base.
When mounted in this manner the grain will be about one centimeter
above the height at which a rock-slice would normally lie on the microscope stage. For this reason it may not be possible to exploit the full
numerical aperture of the high power objective for the examination of
904
M. J. OPPENHEIM
Frc. 1. The mounted spindle stage. The microscope has been fitted with a universal
stage objective (Zeiss UD 20) for conoscopic observations'
interferencefigures unless some adaptation is made to the microscope
substage.on some microscopesit is sufficient to remove the upper stopscrew from the condenserrack, thereby enabling elevation of the condenserlens. Alternatively an accessorylens may be insertedbetweenthe
needleand condenser:the simplest such arrangementis replacementof
the standard condenserby one designedfor conoscopicwork with the
universal stage.
Mrruoo oF UsE
Before use, a few drops of glycerineare inserted within the syringe to
act as a lubricant: the movement thereafter will be at once firm yet
delicate.
A broken-off needle is used for mounting the grain; any available
needlewill serve,such as a domesticor hypodermic type, as long as it is
thin enough to pass through the tip of the syringe. Irregularities left on
the broken needletip should be ground ofi, for they will render cementing
the grain difficult. Dental wax' as recommendedby Rawlins and Hawkstey itsg+) was the first glue tried by the author, and as it has proved
SPINDLE STAGE
905
Frc. 2. I'he spindle stage dismantled. The plastic strip (3 mm thick) is rivetted to the
plywood base plate (5 mm thick) The tube around the syringe housing is to clamp the protractor in place.
l-rc.3.'I'he glass cell (without liquid or cover-slip) Constructed solely of microscope
'I'here
siides glued by dental u,ax.
are no optimal dimensions for the channel: a larger
opening facilitates manipulation but requires more liquid.
M. J. OPPENHL:IM
satisfactory none of the other recipesto be found in the literature have
been tried. The needleneedsbe but slightly warmed before touching it
to the strip of wax; the blob of wax which forms immediately around the
needle tip will remain sufficiently soft during several secondsfor the
attachment of a grain.
After the grain has been mounted on the needle the latter has to be
attached to the plunger. With the plunger in position, the mounted
needleis lifted with forcepsand the sharp end passedthrough the opening
of the syringe and pressedfirmly into the cork which is within the
piungershaft.
Ensuring that the needle is emplaced firmly, the grain is centered,
whiie observingit through the microscope,by manipulating the syringe
bodily within its plastic clamp (Fig. 1); this is a simple and rapid procedure. The plastic tube will retain the synnge rn rts new posltron.
Having mounted and centeredthe grain, a ceil is filled with the selected
liquid and coveredwith a cover slip. The cell is then placed on the stage
and brought up carefully until the grain is enveloped.Once in pla,ce,the
cell is clampedwith one or both of the stageclips. Optical observationsof
the grain may now be begun.
Liquids are changedafter removing the celi and brushing it in a small
bath of acetone.The celi is chargedrvith the new liquid, a cover slip put
on, and returned to the stageas before.
Aovar.tracps oF THE Dosrcx
Nlechanicalperformanceof the stageis good. Nlovement of the spindle
is free yet amenableto precisecontrol, and the grain may be rotated a full
360 degrees.The removability of the glasscell facilitatesits washing,aithough further cells may be held ready for immediate interchangewithout pausingto wash the first one.As severalneedlesmay be kept to hand,
a seriesof pre-mounted grains may be speedi}y examined. X'Ieasured
grains may be stored in their original orientation, or perhapstransferred
to a mounting on an r-ray machine.
AcrNowreocMENT
The author wishes to thank his dentist, Dr. n,I. Wiener, for kindly
providing the wax.
RrlrnnNcns
Rawr.rxs, F. I. G. aNo C. W. Hnwxsr.nv (1934), A cell for refractivity measurements on
minute cr)'stals . f our. Sc'i. Instruments,Il, 282-28+
Wrrcox, Rav E. (1959), Use of spindle stage for cletermining refractive indices of crystal
fragments Am. Mineral., M, 1272-1293.
Manuscript receiaeil,November 25 , 1961.
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