50 



HAND AND OTHER APPARATUS. 



hung over the door. The apartment will now be 

 found to be completely light tight. 



The advantage of the paper walls is that a window 

 can be cut in any convenient part, and a couple of 

 sheets of ruby glass a little larger than the orifice 

 fastened over it, by a few strips of orange paper 

 pasted round their edges. 



The best position for the window is four feet from 

 the floor in the longest side, and the same distance 

 from the wall opposite the door. 



Underneath the window a wooden trough lined 

 with lead, about three feet long, eighteen inches 

 wide, and three inches deep, is fixed ; it should have 

 a gradual incline towards a hole in its centre, where 



Fig. 22. 



