APPENDIX B 369 



with moisture a roll of films should not be left in a camera over twenty- 

 four hours. 



Tank development is best for the field. The tanks provided for 

 developing by the Kodak Company are best for fixing also. A nest of 

 tanks would be a convenience; one tank should be kept separate for 

 the fixing-bath. As suggested in the Kodak circular, for tropical devel- 

 opment a large-size tank can be used for holding the freezing mixture 

 of hypo. This same tank would become the fixing tank after develop- 

 ment. In the rainy season it is a difficult matter to dry films. De- 

 velopment in the field, with washing water at 80° F., is a patience-try- 

 ing operation. It has occurred to me that a small air-pump with a 

 supply of chloride of calcium in small tubes might solve the problem of 

 preserving films in the tropics. The air-purnp and supply of chloride 

 of calcium would not be as heavy or bulky as the tanks and powders 

 needed for development. By means of the air-pump the films could 

 be sealed in tin tubes free from moisture and kept thus until arrival at 

 home or at a city where the air was fairly dry and cold water for wash- 

 ing could be had. 



While I cordially agree with most o^ the views expressed by Mr. 

 Fiala, there are some as to which I disagree; for instance, we came 

 very strongly to the conclusion, in descending the Duvida, where bulk 

 was of great consequence, that the films should be in rolls of ten 

 or twelve exposures. I doubt whether the four-barrel gun would be 

 practical; but this is a matter of personal taste. 



