VARLEY NACHET. 



these tables are made with, a plate-glass top, and surrounded by 

 drawers, in which the apparatus can be conveniently assorted. 



MB. VARLEY'S MICROSCOPE. 



87. This artist has constructed instruments with provisions 

 similar to those already described ; they are somewhat different in 

 their form and details. He has, however, recently introduced a 

 microscope, which claims the advantage of enabling the observer to 

 examine living objects, such as animalcules, notwithstanding the 

 inconvenience arising from their restless mobility, causing them 

 continually to escape from the field of view. The stage motion 

 with its appendages, contrived by Mr. Yarley, enables the 

 observer, without difficulty, to pursue the object. 



He has also contrived a phial-microscope, by which aquatic 

 plants and animals can be conveniently observed. 

 M. NACHET'S MICROSCOPES. 



88. M. Nachet, of Paris, has acquired an European celebrity for 

 the excellence of his instruments, and for the various inventions 

 and improvements in their construction, by which he has extended 

 their utility. He has constructed instruments in various forms, 

 according to the uses to which they are to be applied and their 

 price. For medical and chemical purposes, the body of the 

 microscope slides in a vertical tube, the coarse adjustment being 

 made by a rack and pinion, and the fine by a screw. The stage 

 is firmly fixed under the object-piece, at the top of a hollow 

 cylinder, within which the illuminating apparatus and other 

 appendages are included. 



89. One of the most recent novelties due to this eminent artist, 

 is a form of microscope by which two or more observers may, at 

 the same time, view the same object, thus conferring upon the 

 common microscope a part of the advantages which attend the 

 solar microscope. This is accomplished by connecting two or 

 more tubes, each containing its own eye-piece, with a single tube 

 containing an object-piece ; it has been already shown that the 

 axis of the tube containing the eye-piece may be placed at any 

 desired inclination, with that which contains the object-piece, by 

 placing in the angle formed by the two tubes, a reflector, or 

 reflecting prism, in such a position, that the pencils of rays pro- 

 ceeding from the object-piece shall be reflected to the eye-piece, 

 without otherwise deranging them. It is evident, therefore, that 

 if the rays proceeding from the object-piece could be at the 

 same time received by two or more reflectors, so placed as to 

 reflect them in two or more directions, they might be transmitted 

 along two or more tubes in these directions to two or more eye- 

 pieces, through which the same object might thus be viewed at 



85 



