The Microscope. 30Y 



t/o mm. Bausch & Lomb, Rochester, N. Y. 



15-2 mm. Carl Zeiss, Jena. 



T50- mm. Zeiss for his Apochromatic oil immersions. 



j^ (The Guncllach Optical Co., Rochester, N. Y. 



r^o mm. -^^ ^ j -^^^^^ London. 



if^i-t mm. J. Zentmayer, Philadelphia. 



jLo-_yJi mm. Nachet et Fils, Paris. 



tVo mm. Swift & Son, London. 



The glass, which is said to be crown glass, from which the 

 covers are made, is brittle, and until the microscopist becomes 

 somewhat of an expert he will break them with amazing 

 facility. The skill needed in handling the fragile things is easily 

 acquired, but reasoning from the number of devices recom- 

 mended for the purpose, their inventors have despaired of 

 acquiring that skill themselves, and have judged othei's by their 

 own standard. Many and peculiar cover glass forceps are ob- 

 tainable, all more or less useful, perhaps, but I have never tried 

 them, having always relied on my fingers alone. The simplest 

 device, and one readily made by any novice, is the following, 

 recommended by Mr J. C. Douglas, in the Journal of the Boyal 

 Microscopical Society for 1881, where he says that be long 

 wanted " a simple appliance for picking covers out of the 

 liquid in which they may be soaking, selecting them from their 

 box, placing them flat upon the object to be examined. or 

 mounted, and picking them off the slide when necessary after 

 examining the object covered. Forceps and needles have grave 

 inconveniences. Chase's mounting forceps simply drop on the 

 cover, and are inferior, botli in simplicity and utility, to the fol- 

 lowing plan : Cut a piece of suitable size from a flat rubber ring ; 

 fix this, by a large headed pin, cut short, on to the end of a 

 cedar stick, di'iving the head of the pin so as to form a depres- 

 sion in the rubber ; wet the rubber, and on pressing it against a 

 cover glass it will adhere to it, and the glass may be manipu- 

 lated as desired. To disconnect the rubber from the glass, it is 

 merely necessary to incline the stick so as to detach the rubber 

 at one edge, when the adhesion ceases at once. The apparatus 

 is more durable if a little cementing material be used on the 

 stick, as the pin sometimes draws through the rubber." 



Personally I prefer to get along without any other help than 

 a fine needle in a match handle, using the needle to lift the 

 cover so as to take it in the fingers, and also as a means to lowey 



