The Microscope. 26T 



the'cover glass in changing lenses after using a low power as a 

 finder. This safety spring admitted of an unpleasant pressure, 

 sometimes causing the mounting fluid to swell over the cover 

 glass, sometimes getting on to the lens, greatly to my annoy- 

 ance. At this juncture I looked about me for a better remedy 

 than the safety nose-i)iece to use in my studies of objects on 

 slides not finished by drying and sealing in a permanent mount. 

 I then began to use the short slide, as presently to be described. 

 It was a new idea to me ; whether new or not to other and more 

 experienced workers, I cannot tell, but I do not remember hav- 

 ing ever seen it mentioned in any of the microscopical books or 

 journals at my command. I formed, in this way, a preference 

 for slides two inches long and seven-eighths of an inch wide, 

 finally coming down to one and three-quarter inches long and 

 corresponding in length with tlie excellent short slides furnished 

 by the Bausch & Lomb Optical Co., and very nearly correspond- 

 ing with the length of the German slides furnished by Zeiss, of 

 Jena, and to be had of Emmerick, in New York. Both of these, 

 however, I found too wide for using as safety slides with my 

 apparatus, the opening in the slide carrier on my No. 500 

 Bausch Si, Lomb stand being just an inch wide. I therefore was 

 obliged to get the best, clearest glass I could find, .ind make my 

 own slides, seven-eighths and three-quarter inches wide by 

 one and three-quarter inches long. A fine file or a piece of 

 scythe whet-stone rubbed over the edges and corners removes 

 any sharpness, and is quickly done. A thousand slides of this 

 kind can easily and quickly be made, and will answer every 

 purpose in ordinar}"- work. By mounting the object in one end, 

 I have a safety slide. 



Place the slide so that the mounted end, when projecting over 

 the opening in the stage, is free in air. Now it is apparent that 

 when thus placed under the close-working objective, it cannot 

 be injured, because, when the point of the objective presses on 

 the cover glass ever so slightly, it can make no more than this 

 slight pressure, for the slide, being placed see-saw-like over the 

 opening, will begin the dip of the see-saw motion and tell me 

 that closer racking is useless. In this way I avoid the great 

 care that is necessary in using the old three-inch or long slide 

 with the mount in the middle. This is without the least possible 

 danger of injury to either the mount or the objective, while that 



