huntington] LANDSCAPE NATURE, II 199 



paper used. Each individual must learn to judge these factors 

 by experience. With a thirty-two candle power light, a "normal" 

 negative, and a distance of two feet, an exposure of thirty seconds 

 would be a good time to start with. Since there is no "normal" 

 negative, the time factor is very variable, and it must usually 

 be judged for each negative separately. 



After exposure, the paper is removed from the printing frame 

 and developed with the emulsion side up until the image is nearly 

 of the desired degree of intensity. It is then rinsed in clean water 

 and immersed in a fixing bath, face downward, fixed and washed 

 just as a negative would be. After washing the print is laid 

 face downward on a piece of clean white cloth to dry. 



Cyko is probably the best paper for the use of beginners as it 

 develops slowly, and if over-exposed, its development can be 

 checked by transferring the print to the fixing bath; it will pro- 

 duce excellent prints and will stand a great deal of abuse. It is 

 made in a variety of grades, but the "Normal" will serve nearly 

 every purpose. "Normal contrast" is adapted for use with flat 

 or thin negatives, and "Soft" for negatives that are too contrasty. 



Azo is a cheap paper that is easy to work with, and which will 

 give fairly good prints. 



Velox is probably the best paper made but is very difficult to 

 use since it develops so rapidly that it is practically impossible to 

 check the development of an over-exposed print. 



The above, or any other papers, may be purchased in dozen- 

 sheet packages in any size that one's negatives may be. The 

 printing frames are also made in all sizes. 



M-Q (metol-quinol) is the most widely used and probably the 

 best developer for prints; it should not be used to develop plates. 



Armor Plated Reptile Lived 8,000,000 Years Ago 



Dr. Leonard Keene Hirshberg, A.B., M.A., M.D. 



(Johns Hopkins University) 



Many interesting facts, hitherto un-established, were recently 

 revealed by investigations conducted by the section of fossil rep- 

 tiles of the United States National Museum concerning the giant 

 fossil reptile known as the stegosaurus, or plated lizard. 



It is now known that the two rows of great dermal armor plates 

 along the monster's back alternated like cross-cut saw teeth, and 



