Illuminating Apparatus.
Reading edition
a. Illuminating Apparatus of Stands A and I.
The apparatus includes the following parts:
Cylinder iris diaphragm. Swing-out condenser. Diaphragm carrier with iris diaphragm. Plane and concave mirror.
The cylinder iris diaphragm comes into play when the condenser is swung out of position. To do this the diaphragm carrier is turned to the side as shown in the diagram, a small knob is pressed, which liberates the condenser, and the latter is swung out to the side.
The regulation of the cylinder iris diaphragm is accomplished by means of a lever. Before the condenser is swung back into position the cylinder iris should be opened to its fullest extent. The lower iris diaphragm is for use in connection with the condenser only. It is regulated by means of a small knob. A horizontal rack and pinion arrangement permits oblique illumination, and a vertical rack and pinion permits adjustment of the whole sub-stage. By these means a most perfect control of the illumination of the object is assured. Ground or colored glass discs may be inserted above the iris diaphragm if modification of the light is desired.
$30.—
This illuminating apparatus may also be fitted to Stands Ia and Ib.
Abbe's Illuminating Apparatus for Stand A and I. Swing-out Condenser. Cylinder Iris Diaphragm.
b. Illuminating Apparatus of Stands Ia and Ib (p. 30, 32, 34).
The following are the parts of this apparatus:
Cylinder diaphragm with 3 stops of different apertures. Condenser. Diaphragm carrier with iris diaphragm. Plane and concave mirror.
To substitute the condenser for the cylinder diaphragm the diaphragm carrier is turned to the side and the cylinder diaphragm is drawn out of the sleeve which holds it in position and into which the condenser readily fits. The diaphragm carrier is then turned back into position and the amount of light regulated by manipulating the knob controlling the size of the iris. The whole sub-stage may be raised or lowered in the optical axis by means of a rack and pinion, and a similar arrangement permits lateral illumination by moving the iris diaphragm in the horizontal plane.
Ground glass and colored plates may be inserted above the iris diaphragm.
$24.—
c. Illuminating Apparatus for Stand II and IIa (p. 36 & 38).
The condenser and iris diaphragm form one piece, giving central but no oblique illumination. The whole apparatus may be raised and lowered in the optical axis by means of a screw. The cylinder diaphragm may be inserted in place of the condenser. A ring below the iris diaphragm permits the insertion of glass discs for the purpose of modifying the light.
$12.—
d. Illuminating apparatus for Stand IIb (p. 40).
The same as for II and IIa fitted in a fixed sleeve; without the side-screw.
$10.—
e. Small Illuminating Apparatus.
Small Illuminating Apparatus.
The small illuminating apparatus consists of a somewhat smaller condenser with iris diaphragm and can be adjusted to the Stand IV, when it has the cylinder diaphragm.
$8.—
Cylinder iris diaphragm.
A cylinder iris diaphragm can be furnished in place of the ordinary cylinder diaphragm of Stand II, IIa and IIb at an additional cost of
$6.—
Iris diaphragm fitted to stage of stand III.
Stand III can be had with iris diaphragm fitted in stage, in place of the wheel diaphragm (see page 43) Additional price
$6.—
Complete Microscope Outfits.
The outfits comprised in the following pages are made up with achromatic objectives, which suffice for all ordinary needs.
We are glad to supply any other combination of eye-pieces and objectives which may be preferred. The price of each outfit may be readily computed by adding together the cost of its various items.
Microscope stands, without objectives, will not be sold separately.
Stand A.—Universal Microscope.
Stand "A".
Universal Microscope.
In the construction of our new stand "A" we have taken special care to enlarge all the parts proportionately in order to secure strength and stability, at the same time adding to the beauty of the instrument.
The upper pillar of the microscope is shaped in such a way as to form a convenient handle; and to increase the free working space over the stage, thereby allowing the examination of very large specimen and culture plates. A specially constructed mechanical stage larger than No. 98 may be attached, which is adapted for slides up to 2×4 inches (50×100 mm).
The extra large dimensions of all the main parts of this microscope such as the base and stage etc., allow that freedom of movement so desired in a stand for photo-micrography.
Both the body tube and graduated draw tube are very wide and permit the use of low power objectives to cover specimen of large extent; for the same reason the opening in the stage is very wide but can be narrowed down by a stop.
The most important innovation on the microscope is the new fine adjustment device, which is unexcelled both in solidity of construction and accuracy of movement, representing the highest attainment of the designers and mechanics skill.
Sectional cuts of this unique arrangement are shown in illustration (p. 26-27).
All that can be seen on the exterior are two small milled heads mounted below and somewhat back of the two larger knobs controlling the rack and pinion (coarse) adjustment of the microscope. The knob on the right side is provided with a graduated drum r, indicating the movement of the fine adjustment.
The two knobs with drum are mounted on an axle a, which in its central portion is enlarged and provided with a worm gear. The latter in its turn drives the gear wheel, d. A spiral spring pressing against one of the journals into which the axle is mounted prevents any lost motion in the worm gear. Mounted on the same shaft with the gear-wheel d, is a heartshaped cam f. On this cam rests the steel roller g, fitted on the support k, which in its turn carries the microscope tube. By its weight and a spiral spring the latter presses on the cam f, and effects a direct vertical movement.
The periphery of the heart shaped cam f, is exactly symmetrical and mathematically correct. The distance traversed by its curved sides from the lowest to the highest point and vice versa is 3 mm. There are cut 60 teeth in the entire periphery of the gear-wheel d; the number corresponding to one side of the heart-shaped cam or 3 mm elevation, are 30 teeth, therefore 1 tooth means a movement of 3/30 mm or 0,1 mm.
This in turn requires one complete revolution of the axle a, the drum of which is graduated into 100 parts. The value of each division on the drum is therefore 0,1/100=0,001 mm.
This micrometer fine adjustment is exceedingly accurate and reliable, and besides it has the following advantages;
By virtue of its unique construction the movement is continuous, there is absolutely no limit to the motion of the micrometer screw, which may be turned forward or backward as the work requires.
This movement extends in exact ratio to the revolution of the cam for a distance of 3 mm. As another advantage we may mention, that it is almost impossible to break the coverglass of the specimen with this fine adjustment.
Should the objective come in contact with the coverglass and assuming the knob is turned still further then the tube, which is of aluminium and very light would simply rest on the specimen, without breaking the coverglass, as the latter will easily stand the small pressure of the tube and the fine spiral spring.
No. 1. New microscope stand "A" inclinable with hinged joint and clamping lever, fitted with round revolving centering stage, coarse adjustment by rack and pinion, new fine adjustment by micrometer-screw (each division 1/1000 mm.) Wide tube, draw tube with millimeter scale. Large illuminating apparatus with swing-out condenser and cylinder-iris diaphragm $120.—
Apochr. 16, 8, 4, oil-imm. 2 mm. N. A. 1,30 $204.—
Compens. ocular 4, 8, 12, 18 $34.50
Compens. ocular No. 6 with micrometer and drawing ocular No. 93 $18.50
Large mechanical stage No. 99, for object slides up to 2×4 inches $32.—
Triple nose-piece $8.—
———
Magnif. 70—2250. $417.—
No. 2. The same stand and illum. apparatus; Object.: 2, 4, 6, oil-imm. 1/12, N. A. 1,30 Ocul. 0. I. III. IV. V. microm. ocul. II. Triple nosepiece $210.—
Stand I.
Stand I.
No. 3. Large microscope, inclinable, with hinged joint and clamping lever and fitted with round revolving centering stage. Coarse adjustment by rack and pinion, new fine adjustment by micrometer-screw, the head of which is graduated each division = 1/1000 mm. Draw-tube with (see page 25-26) millimetre scale. Large illuminating apparatus with swing-out condenser and cylinder iris diaphragm (illustrated on page 21).
Mechanical stage, No. 98. Triple nose-piece. Drawing eye-piece, No. 93. Micrometer eye-piece, No. 84. Achromatic objectives Nos. 1, 3, 6. Oil-Immersion 1/12, N. A. 1,30. Eye-pieces 0, I, III, IV, V. Magnifications 12—1300 $236.—
No. 4. The same stand and illuminating apparatus.
Triple nose-piece. Micrometer eye-piece, No. 84. Drawing eye-piece, No. 93. Objectives 2, 4, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV, V. Magnifications 33-1300 $210.—
The stand and illuminating apparatus without objectives, oculars and nose-piece $112.—
Stand Ia.
Stand Ia.
No. 4a. Large Microscope, of smaller size than Stand I, fitted with horseshoe foot. The stand is inclinable and fitted with revolving centering stage, coarse adjustment by rack and pinion, fine adjustment by micrometer screw with scale. Draw-tube with millimetre scale. Large Illuminating Apparatus (Cf. p. 22, b) with rack and pinion, and iris-diaphragm with oblique movement. The cylinder-diaphragm and condenser may be readily substituted for one another.
Triple nose-piece. Objectives 2, 4, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV, V. Magnifications 33-1300 $160.—
No. 4b. The same with Illuminating Apparatus.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV. Magnifications 60-1000 $148.—
No. 4c. The same with Illuminating Apparatus.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30. Eye-pieces II and IV. Magnifications 70-730 $136.—
Stand with Illuminating Apparatus, but without objectives, eye-pieces and nose-piece $76.—
The same with Illuminating Apparatus, Swing-out Condenser and Cylinder Iris-diaphragm (p. 20, a) $82.—
Mechanical stage No. 98 can be fitted to this stand; price $28.—
Stand Ia with English foot.
Stand Ia with English foot.
No. 4d. Large Microscope differing from the foregoing (Ia) stand only in being provided with an English foot, which makes the stand somewhat steadier and lighter. The prices and combinations are otherwise the same. Dr. P. G. Unna of Hamburg uses this microscope in his laboratory. The stage revolves and centres. The illuminating apparatus is that described on p. 22, b.
Triple nose-piece. Objectives 2, 4, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV, V. Magnifications 33—1300 $160.—
No. 4e. The same with the illuminating apparatus.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV. Magnifications 60—1000 $148.—
No. 4f. The same with the illuminating apparatus.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30. Eye-pieces II, IV. Magnifications 70—730 $136.—
The stand with illuminating apparatus, but without objectives, oculars and nose-piece $76.—
The stand with swing-out condenser (p. 20, a) $76.—
Mechanical stage No. 98 can be fitted to this stand; price $28.—
Stand Ib.
Stand Ib.
No. 5. Large Microscope, which differs from Ia only in the stage. The stage is fixed and square. The stand is inclinable and has a hinged joint and clamping lever. Draw-tube with millimetre scale. Coarse adjustment by rack and pinion, fine adjustment by micrometer screw with graduated head. Illuminating Apparatus, same as Ia (p. 22, b).
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV. Magnifications 60—1000 $142.—
No. 6. The same with simplified Illuminating Apparatus (p. 22, c).
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30. Eye-pieces I, III, IV. Magnifications 60—730 $120.—
No. 7. The same without Illuminating Apparatus, with Cylinder-diaphragm.
Double nose-piece. Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $74.—
No. 8. The same without Illuminating Apparatus and without nose-piece.
Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $68.—
Stand without objectives and eye-pieces, without illuminating apparatus and without nose-piece $46.—
Stand without objectives and eye-pieces, with illuminating apparatus, without nose-piece $70.—
The same with illuminating apparatus, with swing-out condenser and cylinder iris-diaphragm (p. 22 a) $76.—
Stand II.
Stand II.
No. 9a. Medium Size Microscope, inclinable, with revolving centering vulcanite stage, coarse adjustment by rack and pinion, fine adjustment by micrometer-screw. Draw-tube with millimetre scale. Illuminating apparatus and iris- diaphragm with lateral screw for raising and lowering. A ring under the iris diaphragm serves to hold a ground glass or colored disc. The illuminating apparatus and cylinder diaphragm are easily interchangeable.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV. Magnifications 60—1000 $126.—
No. 9b. The same with Illuminating Apparatus.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30. Eye-pieces II, IV. Magnifications 70—730 $114.—
No. 9c. The same without Illuminating Apparatus.
Triple nose-piece. Objectives 3, 6, 8. Eye-pieces I, III. Magnifications 60—550 $90.—
No. 9d. The same without Illuminating Apparatus.
Double nose-piece. Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $72.—
No. 9e. The same without Illuminating Apparatus and nose-piece.
Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $66.—
Stand with Illuminating Apparatus and Iris-diaphragm, without objectives, eye-pieces and nose-piece. $54.—
The same stand with Cylinder Diaphragm $44.—
Stand with illuminating apparatus, swing-out condenser and cylinder iris diaphragm $60.—
Cylinder iris diaphragm (Cf. p. 23) $6.—
Stand IIa.
Stand IIa.
No. 9. Medium Size Microscope, inclinable, coarse adjustment by rack and pinion, fine adjustment by micrometer-screw. Draw-tube with millimetre scale. Illuminating apparatus and iris-diaphragm with lateral screw for raising and lowering. A ring under the iris diaphragm serves to hold a ground glass or colored disc. The illuminating apparatus and cylinder diaphragm are easily interchangeable.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV. Magnifications 60—1000 $120.—
No. 10. The same with Illuminating Apparatus.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30. Eye-pieces II, IV. Magnifications 70—730 $108.—
No. 11. The same without Illuminating-Apparatus.
Triple nose-piece. Objectives 3, 6, 8. Eye-pieces I, III. Magnifications 60—550 $84.—
No. 12. The same without Illuminating Apparatus.
Double nose-piece. Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $66.—
No. 13. The same without Illuminating Apparatus and nose-piece.
Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $60.—
Stand with Illuminating Apparatus and Iris-diaphragm, without objectives, eye-pieces and nose-piece $48.—
The same stand with Cylinder Diaphragm $38.—
Cylinder iris-diaphragm (Cf. p. 23) $6.—
Stand IIb.
Stand IIb.
No. 14a. Medium Size Microscope, stand inclinable to the extent of 45°, tripod foot, coarse adjustment by rack and pinion, fine adjustment by micrometer screw. Draw-tube with millimetre scale. Illuminating Apparatus and Iris-diaphragm permanently connected and sliding in a sleeve underneath the stage. The cylinder-diaphragm is used in the same manner. A ring below the iris-diaphragm serves to hold a ground glass or colored disc.
Triple nose-piece. Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30. Eye-pieces I, III, IV. Magnifications 60—1000 $104.—
No. 14b. The same with Illuminating Apparatus.
Triple nose-piece. Objectives 3, 6, 8. Eye-pieces II, IV. Magnifications 70—700 $78.—
No. 15a. The same without Illuminating Apparatus.
Double nose-piece. Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $50.—
No. 15b. The same without Illuminating Apparatus and nose-piece.
Objectives 3, 7. Eye-pieces I, III. Magnifications 85—450 $44.—
Stand with Illuminating Apparatus and Iris-diaphragm $32.—
Stand with Cylinder or Wheel-diaphragm $22.—
Cylinder iris-diaphragm (p. 23) $6.—
For the addition to this microscope of a lateral screw for raising and lowering the illuminating apparatus as on Stand IIa, an extra charge of $2.— is made.
Stand III.
Stand III.
Stand III is now provided with rack and pinion coarse adjustment instead of sliding tube. In consequence a nose-piece can be used on it to better advantage. It will be found an excellent laboratory stand at low price.
No. 16a. Medium Size Microscope, non-inclinable stand, coarse adjustment by rack and pinion, fine adjustment by micrometer-screw. The draw-tube has a millimetre scale. Plane and concave mirror. Wheel-diaphragm.
Triple nose-piece. Objectives 3, 6, 8. Eye-pieces I, III. Magnifications 60—550 $66.—
No. 16b. The same without nose-piece.
Objectives 3, 6, 8. Eye-pieces I, III. Magnifications 60—550 $58.—
No. 17a. The same, with double nose-piece.
Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $48.—
No. 17b. The same without nose-piece.
Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $42.—
Stand with wheel-diaphragm $20.—
This stand can be supplied with iris diaphragm in stage (see illustration p. 23) instead of wheel-diaphragm.
Stand with iris diaphragm $26.—
Stand IV.
Stand IV.
The dimensions of this stand are now larger than formerly. The price has not been changed.
No. 18. Small Microscope. Adjustable by sliding tube and micrometer-screw. The draw-tube is graduated in millimeters. Cylinder-diaphragm with sliding sleeve. Concave and plane mirrors, obliquely adjustable.
Objectives 3, 6, 8. Eye-pieces I, III. Magnifications 60—550 $52.—
No. 19. The same.
Objectives 3, 7. Eye-pieces I, III. Magnifications 60-450 $36.—
No. 20. The same without Cylinder Diaphragm, with Wheel Diaphragm.
Objectives 3, 5, 7. Eye-pieces I, III. Magnifications 60—450 $44.—
No. 21. The same.
Objectives 1, 3, 7. Eye-pieces I, III. Magnifications 18—450 $40.—
No. 22. The same.
Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $34.—
Stand with cylinder-diaphragm, without objectives and eye-pieces $14.—
Stand with wheel-diaphragm, without objectives and eye-pieces $12.—
Stand V.
Stand V.
No. 23. Small Microscope. Adjustable by sliding tube and micrometer-screw. Concave mirror.
Objectives 3, 7. Eye-pieces I, III. Magnifications 60—450 $30.—
No. 24. The same.
Objectives 3, 5. Eye-pieces I, III. Magnifications 60—250 $28.—
No. 25. The same. Plane mirror.
Objectives 1, 3. Eye-pieces I, III. Magnifications 18—80 $24.—
No. 26. The same.
Objectives 3. Eye-pieces I, IV. Magnifications 60—105 $18.—
No. 27. Stand without objectives and eye-pieces $8.—
Stand VI.
No. 28. Auxiliary Laboratory Stand, for the examination of trichinae and for searching plate cultures. Very large stage (3-1/2×4 inch.). Adjustable by means of a carefully constructed rack and pinion, rendering it possible to focus objectives of fairly high power. Stand, without eye-pieces, objectives or case $8.—
No. 29. This stand fitted with objective 3, eye-pieces 0 and IV. Magnifications 40 to 100, in mahogany case fitted with lock $18.—
No. 29a. The same stand fitted with eye-piece II and objective having separable front lens, yielding a magnification of 40 and 100 diam $18.—
Glass compressor with graduation $80.—
Glass compressor without graduation, per pair $40.—
Demonstration microscope.
Demonstration microscope with condenser.
No. 30a. Adapted for low and medium power. Square stage with wheel-diaphragm. Adjustment by sliding tube; after being adjusted the tube may be fixed by a ring clamp. Detachable handle. With clip to hold a sketch or label, etc. Stand without objective and eye-piece. $6.—
No. 30b. The same with objective 3 and eye-piece I, magnifying 60 times $14.—
No. 30c. The same with adjusting screw for focussing high power objectives, with condenser and iris-diaphragm, without objectives and eye-pieces $18.—
No. 30d. The same with objectives 3 and 6 and eye-piece I. Magnifications 60 and 255 $38.—
Nebelthau's Sliding Microscope.
Nebelthau's Sliding Microscope.
(Cf. Zeitschrift für wissenschaftliche Mikroskopie, XIII, 1896.)
No. 31. The sliding microscope is an instrument by means of which very large microscope sections, as, for example, large sections of the brain, can be systematically examined. It is also of service in looking over plate cultures of bacteria. The microscope is carried on a heavy beam supported by two stout pillars under which the stage moves. The various movements are accomplished by motion of the microscope on a lateral track upon its support and by motion of the stage on a similar track at right angles to the first. The motion of the microscope is by means of a screw, that of the stage by double rack and pinion. The extent of the movements is indicated in each case by a scale, thus permitting the systematic examination of the entire specimen. The stage consists of a glass plate, measuring 16×20 cm, which is carried in a frame supported on four columns. The tracks permit a motion of the microscope of 18 cm and of the stage of 13,5 cm. A mirror under the stage affords ample illumination. The microscope tube is so arranged that it can be easily removed from the stand and a simple lens substituted for it. The coarse adjustment of the microscope is by rack and pinion. A screw above the objective serves for fine adjustment. The price of this sliding microscope, without objectives or oculars, but with a lens holder and simple lens magnifying eight diameters is $80.—
Flat glass dish of the same size as the stage to hold very large sections for the purpose of examining them while in clearing fluid $1.25
Dölken's Microscope stand.
No. 32. Dölken's Stand. (p. 52) The stand is larger than Stand No. Ia, but is modified as shown in the cut so as to permit the examination of unusually large preparations. It is provided with the illuminating apparatus b (p. 22) and with all the adjustments necessary to the use of high powers.
Stand and illuminating apparatus, without nose-piece $80.—
Travelling Microscope No. 33.
No. 33. Travelling Microscope. This microscope is ready for use after spreading the foot, drawing out the tube and setting the mirror and stage in position. It is provided with all the adjustments of Stand No. V, consisting of fine adjustment by micrometer-screw, coarse adjustment by rack and pinion and illuminating apparatus d (p. 22). The box is arranged so as to accommodate three objectives and two oculars. It locks, has a handle, and measures 25×15×7 cm, the whole apparatus weighing 5 pounds. Price of this microscope with illuminating apparatus, but without objectives or oculars $32.—
The same, without illuminating apparatus $24.—
Large Travelling Microscope No. 34. (Size of mahogany case 28×19×8 cm.)
This instrument (in size like the Ib.) combines all the essential features of a large laboratory microscope with a folding stand. It will be found invaluable on scientific expeditions, for research work etc.
When lifted out of the case, spread the two parts forming the base, which are then held by a spring-catch. After raising the tube, turn the stage around and tighten it by means of a lever. It is supplied with large Abbe condenser and Iris diaphragm adjustable by side screw. Coarse adjustment by rack and pinion, fine adjustment by micrometer-screw. Graduated draw-tube. The stand has joint for inclination.
Large travelling microscope No. 34 (set up).
No. 34. Stand with Abbe Condenser and Iris-Diaphragm, double nose-piece $66.—
No. 35. The same, with objectives 3, 6, Oil-Immersion 1/12", N. A. 1,30. Eye-pieces I, III. Magnifications 60—800 $128.—
Horizontal-Microscope.
No. 36. Horizontal Microscope. This instrument consists of a microscope tube placed horizontally on a long extensible column, supported in turn by a tripod base provided with levelling screws and a round spirit level. The extension of the upright supporting column is accomplished by two sliding motions, the lower, controlled by a set screw only, being intended for coarser adjustments, the upper, controlled by rack and pinion, for finer adjustments. A millimeter scale and a vernier serve to indicate the degrees of the various motions, so that vertical motion of the microscope tube to the extent of 1/10 mm may be accomplished. The microscope tube carries a spirit level and revolves upon a horizontal disc. The objective, consisting of two separable doublets, permits three degrees of magnification of 5, 9 and 48 cm focal distance respectively. A rack and pinion adjustment serves as adjustment of the microscope tube. A micrometer, 1 cm long and divided into 100, in the diaphragm of the ocular still further increases the availability of the instrument for making fine and accurate measurements. The instrument serves as a useful aid in many physical and physiological investigations. Price, including objective, ocular and micrometer $40.—