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which in use is placed in front of a window, in fact is usually at- 

 tached either to the window, the window casing, or to special 

 uprights near by. As exemplified in this laboratory, the appara- 

 tus is attached to two upright girders, the same two that carry 

 the ordinary photographic camera. Both these attachments are 

 slung on sash weights and can be moved up and down, so that 

 either may be brought into play while the other is raised out 

 of the way. The camera lucida attachment consists of two dis- 

 tinct frames which are separated near the middle of the window 

 by a distance of eight to ten inches. The left hand frame is 

 designed mainly to support the camera lucida, the right hand 

 frame to support the drawing board. Both frames carry adjusta- 

 ble brackets and each bracket carries a horizontal shelf. The 

 left hand frame therefore has a horizontal shelf carrying the 

 microscope and this shelf is adjustable in the vertical direction, 

 and can be clamped in any desired position. In a similar man- 

 ,ner, the right hand frame carries a horizontal shelf, or drawing 

 board, also adjustable in the vertical direction. The drawing 

 board presents the peculiarity of being also adjustable in the 

 horizontal direction, and of rotating about a horizontal axis so 

 as to pass the opposite shelf, — it is required sometimes above 

 that shelf and sometimes below it. The size of the apparatus is 

 determined by that of the human body. The greatest distance 

 that can be comfortably reached by an ordinary artist for draw- 

 ing purposes is about thirty inches, i. e., when gazing through 

 the. camera lucida he can not comfortably produce a drawing 

 at a distance of more than thirty inches from his eye as the 

 light travels. An examination of the adjacent illustration will 

 make this matter somewhat clearer. The camera lucida is 

 usually carried on a piece of tubing clamped to an ordinary lens 

 holder or empty microscope barrel. The object to be drawn is 

 placed below, without a lens, or with a reducing lens, or in some 

 cases with a lens which slightly enlarges the object. The draw- 

 ing board is then lowered or raised until the drawing- to be made 

 will have the necessary size. It will be observed therefore that 

 the whole arrangement is a three-fold one. There is a support 

 for the object, a support for the camera, and a support for the 

 drawing board, and these must be adjustable within the limits 

 of the artist's reach. It will be seen however that if two of 

 these are adjustable, the whole system is, for all practical pur- 

 poses, the same as if all three were adjustable. We now come 

 to the most important matter in connection with the use of 

 this apparatus, namely: the illumination of the object and the 

 illumination of the drawing board. It is possible that it is in 

 this respect that the apparatus hitherto put on the market fails 



