62' J. Waterhouse — The Application of Photo grapliy [No. 2, 



poses, and to give a summary of the principal methods that may be usefully 

 employed with reference to the wants of the State or of private individuals, 

 rather than to those of professional cartographers and map -publishers, 

 though the latter may in many cases also find photography a useful auxiliary. 

 Photographic methods can never entirely take the place of lithography or 

 engraving by hand, either for public or private purposes, but their use may 

 be advantageously extended. Those who wish for fuller details may con- 

 sult the text-books by Abney, Carey Lea, Monckhoven, Vogel and others, 

 and the special works referred to in this paper. 



II. Preparation or the Original Drawing. 



I have already adverted to the difficulty that has been found in this 

 country and elsewhere in obtaining original drawings suitable for repro- 

 duction by photozincography, and to the fact that without a proper original 

 drawing it is quite impossible to produce satisfactory results. Besides its 

 principal use in reproducing maps of the Surveys, photozincography is 

 very largely utilised in India by engineers for the reproduction of their 

 plans and drawings, and by other public officers for an immense variety of 

 miscellaneous maps and plans, and as we were constantly asked to photo- 

 zincograph subjects utterly unsuitable to the process, a set of rules for the 

 preparation of the original drawings for reproduction by photozincography 

 was drawn up under General Thuillier's direction and published in the 

 official Gazettes all over India, and the result has been a great improve- 

 ment in the execution of the drawings we receive for reproduction. 



The rules are as follows : — 



1. All drawings should be on white, smooth-surfaced paper, free 

 from dirt, pencil marks, creases and wrinkles. When possible they should 

 remain stretched on the drawing-board. 



2. The Indian ink should be freshly rubbed down and give good hlach 

 lines, free from glaze. 



3. The lines should be firm and cleanly drawn — not too fine or too close 

 together. They must be quite hlach^ and light effects must be produced 

 by fine and open black lines, and never by the use of pale ink. Thick lines 

 in the printing and borders of maps should be well filled in. Pencil marks 

 should be carefully removed, so as not to injure the blackness and firmness 

 of the lines. 



4. All cross-hatching and shading should be as open and clear as 

 possible, and the lines composing it firm and not too fine. Intensity of 

 shade must be shown rather by an increase in the thickness of the lines 

 than by placing them closer together, in order that the intermediate spaces 

 may not become blocked up when transferred to zinc. It is better not to 

 rule the shading of mechanical and architectural section-drawings, but to 



