THE AMERICATn^ MONTHLY 



[May, 



moved independently around the 

 focal point as a centre, and can be 

 used above the stage. The sub-stage 

 and mirror can be clamped in any 

 position. 



The fine-adjustment moves the 

 entire body. The stand is balanced 

 so as to be perfectly stable, when 

 the tube is horizontal. There is a 

 large screw for wide-angled, low 

 power objectives, which Mr. Bul- 

 loch has also applied to his other 

 stands. 



The stage, which is adjustable to 

 the axis, measures three and a half 

 inches in diameter, and is three 

 and a half inches above the table. 

 The stand is twelve and a half 

 inches in height, when standing 

 upright. 



Other details can be readily ob- 

 served by studying the illustration 

 which we give. 



The stand as shown, made of 

 polished brass, with one eye-piece 

 and case, is sold for $40.00. 



Cleaning Foraminifera. 



After having read Mr. Yorce's 

 article on cleaning Foraminifera, it 

 occurred to me to use electrical 

 force to extract the shells in the 

 dry way. For this purj^ose 1 used 

 a small tin lid, four inches in dia- 

 meter, filled with a preparation of 

 rosin and sealing-wax, the resinous 

 surface of which, for convenience, 

 I excited with an artist's brush, 

 known as a " Badger blender." 

 The sand from sponges or fora- 

 miniferous marl is spread thinly 

 over as large a surface as conve- 

 nient ; the cake of rosin is then ex- 

 cited by passing the Badger's-hair 

 brush over it several times, and then 

 turning the excited surface of the 

 resinous cake down to within a 

 quarter of an inch of the material, 

 and passing it gently over it. The 

 result will be that innumerable 



light particles will be attracted to 

 the excited surface, and will remain 

 there, while the sand will be at- 

 tracted and I'epelled back, thereby 

 leaving a large percentage of Fora- 

 minifera, spicules, etc., adhering to 

 its surface, which may then be 

 brushed off into any suitable recej)- 

 tacle. The above plan may be 

 tested on a small scale by exciting 

 the end of a large stick of sealing- 

 wax. Damp weather is unfavora- 

 ble for the experiment. I have 

 found it very successful. 



K. M. Cunningham. 



A Simple Mechanical Finger. 



In mounting objects for the mi- 

 croscope it is often desirable to 

 arrange minute particles on the 

 slide, or to transfer them from one 

 slide to another, or to scrape away 

 dirt. The devices employed for 

 this purpose, so far as I am in- 

 formed, depend upon the lengthen- 

 ing of the part which supports the 

 sub-stage apparatus, by means of a 

 tube specially fitted for the pur- 

 pose, or by means of the parabo- 

 loid, so that, by a rack movement, 

 the slide may be lifted free from 

 the stage into contact with a 

 hair or fine wire, which is held by 

 the stage-forceps, or by some con- 

 trivance designed especially for the 

 purpose. Contact having thus been 

 established, the slide may be low- 

 ered, leaving the object adhering to 

 the hair, or, by moving the sliding 

 stage, the object may be pushed in 

 any direction desired. There is, 

 however, another plan which has 

 occurred to me, and which I find 

 to be simpler, and even more effec- 

 tive, in certain respects. With seve- 

 ral styles of microscopes a condens- 

 ing lens is supplied, which is fitted 

 to the limb of the instrument by a 

 ball-and-socket joint and sliding 



