Untitled record

Application filed February 10,1894. Serial No. 499,783. (No model.)

To all whom it may concern:

Be it known that 1, Hiram G. Sedgwick, a citizen of the United States, residing at Nashville, in the county of Davidson and State of 5 Tennessee, have invented certain new and useful Improvements in Slow-Motion Attachments for Microscopes and other Instruments, of which the following is a specification, reference being had therein to the accompanyio ing drawings.

This invention relates to a slow-motion attachment for use on microscopes and other instruments using or requiring rack-and-pinion adjusting devices, the essential object of 15 the invention being to provide a simple and inexpensive attachment that may be readily attached to and detached from the pinionshaft without in the least mutilating any of the parts or changing their construction.

The device is adapted for attachment to the pinion-shaft that is used for effecting the coarse motion. It is attached on one of the projecting ends of the shaft, outside of the instrument, whereby it may be readily at25 tached to all the compound microscopes now in use without mutilating them or changing their construction or taking them apart, and this whether they be provided with other fine adjustments or not.

The attachment will be best understood by describing the preferred construction; but I wish it distinctly understood that I do. not confine myself to the construction and arrangement herein shown and described as the 35 same may be varied greatly without departing from the scope of the invention in the least.

In the drawings. Figure 1 is a transverse sectional view showing my attachment ap- 40 plied to a microscope; Fig. 2, a transverse section on line 2--2 of Fig. 1, this view being slightly enlarged; Figs. 3 and 4, detail views; and Figs. 5,6 and 7 detail sections showing a slightly modified form of spiral pinion.

Referring to the drawings by numerals, 1 is the microscope tube; 2, the usual rack carried thereby; 3, the usual pinion carried by the shaft 4 and meshing in said rack, said shaft being journaled in the arm 5 of the 50 usual frame and carrying at its ends the usual milled operating heads 6.

On the shaft 4, between one of the milled heads and the adjacent face of arm 5, is mounted the attachment, which consists essentially of a pinion 7 provided with exter- 55 nal spiral ribs or threads and mounted on the shaft in such a manner as to have only a frictional engagement therewith, whereby the shaft and pinion may revolve independently or in unison. To obtain this frictional en- 60 gagement in the simplest manner the pinion is split lengthwise on one side to allow it to be expanded slightly and slipped over the end of the shaft, the width of the slit being just sufficient to cause it to hug the shaft 65 with the desired friction and at the same time without materially mutilating the spiral ribs. Working on this spiral-pinion is an endwisemovable sleeve or tube 8, which is internally ribbed to correspond to the spiral ribs on 70 the pinion and is externally screw-threaded ata suitable pitch. To prevent this tube 8 from rotating and at the same time perihit it to freely slide' endwise, it has one or more longitudinal grooves or ways cut in its ex- 75 terior in which work stationary keys 9, which project out horizontally from a plate 10 secured by screws, rigidly but removably, to the side of the microscope or other instrument, the ends of said keys being preferably 80 connected by a ring 11.

To slide the tube 8 back and forth on the keys, a tube 12 is fitted over it, this tube being internally threaded to correspond with the threads on said tube 8 and being also pro- 85 vided with a milled operating-head 13, which latter is preferably a trifle larger than the adjacent operating-head on the main shaft. The inner end of the tube 12 fits over an annular flange 14 on plate 10 and its outer end fits 90 snugly within a stationary cap 15, whereby the tube is not only kept true but is also prevented from being thrown by the screw against the adjacent milled head 6. The cap 15 is slipped over the shaft and is secured rig- 95 idly to the ends of the keys, or ring as shown.

To rapidly and coarsely adjust the tube of the microscope or other instrument, the heads 6 are revolved in the usual manner. During the operation of coarsely adjusting the tube 100 by said heads the fine adjustment parts all remain inert, the pinion-shaft being permitted to rotate independently of the spiral-pinion by reason of the frictional engagement

528,311 therewith and the spiral-pinion itself being prevented from rotating by being interlocked with the non-rotatable sleeve; but when the head 13 is rotated to effect the fine adjustment 5 of the microscope tube, the threads on the interior of the outer tube 12, engaging with the threads on tube 8, cause the same to move endwise on the keys, and this endwise movement of the non-rotatable part .8 imparts a slight io rotative movement to the pinion shaft through the medium of the spiral-pinion, this pinion gripping the shaft with sufficient tightness to positively rotate it. Thus it will be seen that the slow-motion parts are only operated when 15 the power is applied to the head 13, the fastmotion parts operating precisely in the same way as ususl and wholly independently.

The spiral-pinion or “twisted-gear” 7 may contain any number of teeth from one up20 ward, according to the degree of accuracy desired. As shown in Fig. 5 two teeth or ribs only are employed, two spirally curved grooves being formed in the interior of the endwise movable part to engage said ribs;

but where great accuracy is required, the ribs will be disposed entirely around the pinion as in Fig. 2, as in that case the ribs on one side counteract or take up the loose motion on the opposite side, as is apparent.

0 The advantages of this invention over prior devices of its kind are obvious to any one skilled in the art. Heretofore, slow-motions have not been made in the form of an “attachment,” attachable and detachable at will, 35 but have always been made permanent parts of the microscope or other instruments, having been made at the time the instruments were made, and instruments not provided with the slow-motions had to be sent to the 40 shop and dismantled to have them put on.

Then again the slow-motions heretofore used have been too expensive to be put on any but the finer machines. These serious drawbacks have been long recognized by instrument 45 makers and many attempts have been made toobviate them without material success; but it is believed the present invention overcomes said objections, since it may be readily attached to any instrument using a rack50 bar and pinion without mutilating or dismantling the instrument and by any person of ordinary intelligence. It will be seen that the device is adapted for attachment directly to the coarse-motion shaft in the space that 5 5 usually exists on all instruments between the side of the instrument and the usual milledhead.

To attach the device it is simply necessary to remove one of the milled-heads and slip 60 the parts of the device on the shaft and then replace the milled-head. Of course, a couple of small screw-holes must be made in the instrument for the reception of the securingscrews. Thus it will be seen that the appli65 cation of this device to any of the instruments now in use—whether they be provided with other more complicated slow-motions or not—involves but a small expense and but little trouble.

Besides the advantages of simplicity and 70 general applicability, thus obtaining the slow-motion through the medium of the same shaft and pinion that effects the fast-motion it has other advantages perhaps more important. In the most practical devices heretofore 75 in use, the slow-motion has generally been obtained by means of a double-slide arrangement and micrometer screws, as is well known, but this arrangement of two slides is defective for use with high-power objectives for the 80 simple reason that it is a practical impossibility to obtain perfect parallelity of the working-faces of the slides, in consequence of which the object is frequently thrown or shifted about the field when the slow-motion 85 is resorted to. This “side” or “upwardthrust,” as it is called, is more nearly obviated by using but one sliding surface and effecting both the course and fine adjustment of the tube through the single pinion, as is 90 evident.

I have found in practice that a higher degree of accuracy can be obtained with my simple device than can be obtained with the expensive compound-slide devices heretofore 95 used. It will be seen that simply by increasing or diminishing the pitch of the threads on the sleeves and the spiral-ribs on the pinion, almost any degree of fineness and precision in slow-motion may be obtained, ac- 100 cording to the character of the instrument.

It will be understood that this attachment is applicable to instruments other than microscopes. For instance, it may be used on telescopes, photographic cameras, stereopti- 105 cons, and other instruments where rack-andpinion movements are used and a slow-motion is desired. It will therefore be understood that wherever I use the term “instrument” in the claims and in the specification no I mean any instrument to which the device is applicable.