1893.] THE MICEOSCOPE. 4l 



A PNEUMATIC BUBBLE REMOVER. 

 By A. P. Weaver, 



JACKSON, MISS. 



Being; annoved with air bubbles in mv mounts, I have made a 

 simple air-pump for removing them, as follows : Take a small 

 rubber syringe, the packing on the cylinder of which ought to be 

 adjustable so as to fit the body of the syringe rather tightlv ; cut oft' 

 the nozzle rather close to the body, and bore a hole 3 mm. in di- 

 ameter near the top of the latter, so that the packing will always 

 be below the hole. Cut from an old rubber boot two washers 

 2.5 cm. in diameter and with a central aperture of 2 c.?n. : cement 

 these washers together with Red Cross cement (such as is used 

 for mending punctures in pneumatic bicycle tires) ; cut from the boot 

 two more washers of the same outside diameter and with a cen- 

 tral hole a little smaller than the nozzle of the syringe ; cement 

 these last two washers together also, and cement them to the first 

 two prepared ; you will now have a shallow chamber a little 

 larger than the cover-glass. Force the nozzle of the syringe 

 through the opening in the two top plates and firmly cement it 

 there. All these joints must be air-tight. 



To use the instrument, place the slide on a smooth surface, 

 wet the under surface of the rubber washers and apply the same 

 to the slide with the cover-glass in the shallow chamber. To 

 make a good air-tight contact with the slide, grasp the syringe 

 with the left hand and allow the lower side of the latter to hold the 

 washers firmly to the slide. The hole drilled in the syringe is to 

 act as a trap or valve and is to be tightlv covered with the first 

 finger of the left hand (keeping the latter in position, grasping 

 the syringe and holding the washers to the slide) at each downward 

 stroke of the piston and uncovered at each upward stroke. This 

 is, of course, done to prevent the entrance of air to the vacuum 

 chamber beneath, after it has once been exhausted. I have found 

 that three or four strokes are sufficient to bring; all bubbles to the 

 surface of the mounting: fluid and cause them to burst. 



MICROSCOPE EYEPIECES. 

 By O. Beckerlegge. 



There is this difference between the eyepiece of a telescope 

 and microscope : on a telescope a much higher power can be used 

 than on a microscope. In the former a long focus object-glass is 

 used ; consequently the image is not magnified to any great extent : 

 the main magnification is made by the eyepiece. In the micro- 

 scope the object-glass is of short focus, and consequently magni- 



