HAKDWICKE'S SCIENCE-GOSSIP. 



265 



THE MICEOSCOPE AND MICROSCOPIC WOEK. 



No. XII.-By F. KITTON. 



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E have endeavoured 

 to describe the pro- 

 gress made in the 

 construction of the 

 microscope since its 

 invention by Za- 

 charias Jansen in 

 1590, and have also 

 glanced at the work done with 

 them, and shown that it has in 

 very many cases been valuable; 

 but little or no preparation of 

 the objects for examination 

 seems to have been made. 

 Swammerdam was famous for 

 his minute dissections, but no 

 attempt, it appears, was made 

 to preserve them. It is true 

 Lieberkuhn in the early part 

 of the last century mounted 

 injected preparations on small 

 discs of metal ; these were afterwards covered with 

 varnish, which dried with a convex surface. Slides 

 of microscopic objects were also sold by Cuff, 

 Adams, and other opticians : these were slips of 

 ivory, about three-eighths of an inch in width, and 

 three inches in length, in which four cells were 

 made. The bottom of the cell had a narrow rabbet 

 to prevent the small disc of talc upon which the 

 object was placed from falling through : a second 

 disc of talc was used as a cover, and secured in its 

 place by a split ring. Some of these slides in our 

 possession (sold with an Adams microscope made 

 in 1757) contain the following objects :— Elea, louse, 

 cheese-mite, wing of fly, foot of spider, feathers of 

 butterfly, section of elder-pith, piece of muslin, leaf 

 of moss {Sphagnum), mouse-hair, human hair, wool, 

 silk, &c. Most of these are scarcely recognizable, 

 and although mounted as transparent objects, are 

 really not so ; the flea, for example, had been simply 

 killed and placed between the two discs of talc. 

 No. 144. 



Nothing, of course, but the outline, even in its best 

 condition, could have been seen. Pritchard, as late 

 as 1832, gives directions for mounting transparent 

 objects in ivory sliders, and cautions the student 

 against dusting the micas with anything but a 

 camel's-hair pencil, and never to touch them with 

 the fingers. 



He further describes a new method of mounting 

 minute transparent objects in brass sliders : — " Pro- 

 cure a piece of latin brass, about the thickness of 

 note-paper, and cut off a slip the length of the 

 intended slide and twice its breadth ; then fold it 

 down the middle, and make a small hole for the 

 object. Now take a piece of talc a little narrower 

 than the brass, and make a slit down the middle, 

 leaving a portion uncut at either end, so as not to 

 separate it ; then put in your object, and fold it as 

 you did the brass ; lastly insert the talc thus folded 

 between the sides of the brass, and pinch the latter 

 close, and the slider is completed. As their size 

 need not exceed that of the diagram — this is 1£ 

 inch long by \ of an inch wide — several of 

 these sliders may be carried in a pocket-book, and 

 are always ready to examine the merits of any 

 instrument that may present itself." 



The plan adopted for fluid-mounting would, we 

 imagine, be far from successful. We are told to 

 take a slip of glass, and spread a little white lead 

 ground in oil, leaving an aperture in the middle to 

 receive the object. This paint being laid on of the 

 thickness of the object, the little pool or cavity is 

 filled with weak spirits of wine ; then lay in your 

 object. Having cut a piece of talc the proper size, 

 lay it on the top, and with a stick of wood rub it 

 close down on the paint, beginning at one end and 

 passing across the slider to the other, so as to ex- 

 clude air-bubbles. Opaque objects were to be 

 mounted on little discs of blackened cork. 



The following directions how to perform a little 

 bit of microscopic conjuring will perhaps interest 

 some " microscopists." Procure 



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