52 HAND AND OTHER APPARATUS. 



It will be seen by the figure that, in the unoccu- 

 pied portion of the paper wall next the door, about 

 three feet from the ground, a window twelve inches 

 wide and about four or five feet long, has been cut, 

 a board two feet long the same width as the window 

 projects from its lower end into the room, where it 

 rests on a support which keeps it perfectly level. 

 Two laths op posts are erected at the dark room ex- 

 tremity of this platform, and the whole covered over 

 with newspapers and tarred paper, the same way as 

 the dark room itself; a reference to fig. 26 will ex- 

 plain this better than any words can do. 



A recess is thus formed in the wall outside of the 

 dark room. Inside the dark room in the side walls 

 of this recess, two windows about a foot square are 

 cut, and covered with sleeves of black cloth, fastened 

 at their open ends with indiarubber. 



In the partition between the dark room and in- 

 terior of the recess, between these two walls an ori- 

 fice is made, about thirty inches in diameter also 

 covered with a sleeve of black cloth. 



The legs of the stand described in the previous 

 chapter are taken off, plank no. 1 from which the 

 camera is detached folded beneath 2 and 3, and 

 placed in this recess with the microscope towards 

 the dark room, all the necessary manipulations to be 

 described in future pages, are carried on by the arms 

 passed through the two sleeves situated at the side 

 of the recess. The third sleeve is fastened round the 

 tube of the microscope, and the fine adjustment 

 screw, the milled head being removed, passed 



