OF ARTS AND SCIENCES. 247 



read the finest type, and the light pervading the whole room is very 

 satisfactor}-. After a short exposure to it, in fact, it seems almost like 

 white light. 



In this connection may be mentioned a device which has proved 

 very useful as an auxiliary in enabling one to judge of the proper de- 

 velopment of a negative. A square hole measuring an inch and a 

 half on a side is cut in the upper portion of the Golden fabric, and a 

 piece of red glass inserted between the two thicknesses. If a negative 

 be now held near this hole, a red square of light will be cast upon it. 

 This square can be seen even when the lights of the negative are quite 

 intense, and by noting its distinctness, one can judge of the opacity of 

 the high lights as accurately as he can of the details of the shadows 

 of the picture. If the high lights reach their proper intensity first, he 

 develops for the shadows, and vice versa. 



As the whole question of the proper medium to use resolves itself 

 merely into what part of the spectrum to employ, red, orange, or 

 orange-yellow, and all three of these yield nearly equally good results, 

 it is evident that no important improvement can be made in the future. 

 But as the orange-yellow is much the pleasantest light of the three, 

 and seems to give rather less fog than either of the others, it is the 

 color to be recommended. Any medium which will transmit this 

 color will be found satisfactory, but Golden fabric is perhaps as 

 convenient as any. 



A very portable form of lantern to be used when travelling consists 

 of a strip of Golden fabric a foot wide by two and a half in length. 

 When one wishes to use it, it is rolled into a cylinder a foot long, and 

 five inches in diameter, and pinned. A kerosene lamp with the wick 

 turned down low, or a candle, is then placed inside, and the lantern is 

 complete. The circle of white light formed on the ceiling is not bright 

 enough to do any harm. The lantern is set several feet away from 

 the exposed plates, and they should in general be protected as much 

 as possible from direct illumination. There is then plenty of light, 

 and yet not the slightest danger of fog. 



