76 



Journal of Applied Microscopy. 



ered from the nozzle in single drops or 

 in a steady stream according to the 

 degree of pressure exerted upon the 

 tube over the bead. In preparing this 

 apparatus I have used glass tubing 

 measuring 7-32 inch outside diameter, 

 and red or antimony rubber tubing 

 measuring 5-32 inch inside diameter. The 

 bead can easily be made from a piece of 

 glass rod, and should, as I have said, 

 be made a trifle larger in diameter than 

 the inside diameter of the rubber tub- 

 ing. It should also be as nearly circula; 

 as possible, at least in one plane, iv 

 order to close the tube tightly and 

 uniformly. 

 The advantages of this apparatus are: 



(1) that the bottle is fairly germ-proof 

 and might be made entirely so by plug- 

 ging the tube admitting air with cotton, 

 the water thus maintaining its purity 

 unimpaired if it be originally distilled; 



(2) that the disagreeable results which 

 attend the constant use of an ordinary 

 wash-bottle where the lips are applied 

 to one of the tubes, are entirely obviated; 



(3) that the flow of water is under per- 

 fect control; and (4) that it renders 

 unnecessary the constant shifting of the 

 bottle from place to place. The bottle 

 remains stationary and the slide is 

 placed under the nozzle, which may be 

 adjusted to any height desired by rais- 

 ing or lowering the discharge tube. The 

 whole apparatus is of simple construc- 

 tion and may be made very durable by 

 using a bottle of heavy glass. 



W. C. Sturgis. 

 Connecticut Agricultural Experiment 

 Station, February, 1898. 



A Marker for the Microscope. 



Several years ago, having need of a 

 marker for use in certain work which 

 was then going forward in my labora- 

 tory, I made some rough sketches from 

 which the university mechanic made a 

 somewhat clumsy but very useful at- 

 tachment to the microscope. It has since 

 been used successfully by many workers 

 and may be fairly said to accomplish its 

 purpose. The accompanying drawings 

 will enable any one to understand its 

 construction, and if he is able to handle 

 tools make one for himself. 



It consists of a base "C," having on one 

 side a screw thread "B," by which it may 

 be attached to the nosepiece of the mic- 

 roscope. Through this base a sunken 

 screw, "A," fastens to the revolving 

 plate "D," which in turn carries the 

 grooved post "H." Over this post there 

 is slipped the adjustable collar "P," 

 which is tightened and held in place by 

 the set screw "A." The small camel's 

 hair brush "G" is slipped between the 



post and collar in a position opposite to 

 the set screw, as shown in Fig. 3, where 

 it is exactly in the axis of the micro- 

 scope. It is obvious that if now the plate 



Fig. 2. 



Fig. 1.— The marker complete, with brush "G" in 

 in place. Fig. 2.— The same with the adjust- 

 able collar "F" removed. 



"D" be rotated the brush will make a 

 revolution upon its own axis, but if the 

 position of the brush be changed by 

 rotating the collar upon the post, then a 

 rotation of the plate "D" will cause the 

 brush to rotate around an axis at a 

 greater or less distance from it. In 

 other words, the brush will describe a 

 circle of greater or smaller dimensions. 

 In using it our practice has been to at- 

 tach the marker to the double or triple 

 nosepiece of the microscope, and when- 

 ever an object was to be marked, to bring 

 it exactly into the center of the field and 

 then to swing the marker in place of the 

 objective, racking it down so that the 

 brush touched the cover glass lightly, 

 then with a careful turn of the plate 

 "D" to run a ring around the object. We 

 have used asphalt thinned with turpen- 

 tine, and find it to be quite satisfactory. 

 Care must be taken not to apply too 



Fig. 3. — Top view of Fig. 1. 



much asphalt, and special care must be 

 taken to have the brush well pointed, 

 otherwise the asphalt ring will be broad 

 and unsightly. Of course these rings 

 must be made of larger or smaller 

 dimensions, to suit the object which they 

 serve to mark. Charles E. Bessey. 



University of Nebraska. 



