TRANSACTIONS OF SECTION E. 629 



(1.) Rapidity of production and multiplication. 



(2.) The perfect fidelity with which the most delicately minute and intricate 

 details are copied. 



(3.) The facility with which copies may be obtained on scales larger or smaller 

 than the original. 



(4.) The comparative cheapness of the photographic methods. 



Notwithstanding these advantages, the use of photography as a means of repro- 

 ducing maps for publication has not extended so much as might have been ex- 

 pected, in great part owing to the difficulty of making draughtsmen fully under- 

 stand the requirements to be fulfilled when preparing maps for reproduction, in 

 order to produce satisfactory results, and that they must strictly refrain from 

 using colour, and draw the map neatly in black and white, so that every line may 

 be reproduced of its proper strength, according as the map is to be copied on the 

 same scale as the original, or to be reduced. 



Captain Waterbouse described at considerable length the following pro- 

 cesses : — The production of the negative ; photographic printing on sensitive paper ; 

 photolithography and photozincography ; photo-Collotype ; Woodburytype ; pho- 

 tographic engraving ; phototypography, and several miscellaneous processes, such 

 as blue prints, bichromate prints, and polographing on copper. 



3. Eichthofen, Prejevahhj, and Lake Lob. By E. Deluar Morgan, F.B.G.S. 



SATURDAY, AUGUST 17, 1878. 

 This Section did not meet. 



