On a new Photo-Lithographic Process. 173 



quently speak at greater length, have turned their attention 

 to photo-lithography. 



It is not my intention to undertake the description and 

 criticism of the majority of these important inventions, 

 save as far as they stand in close relationship to the subject of 

 this paper. The invention I have been fortunate enough to 

 make belongs to the latter class, and I shall describe it as con- 

 cisely as possible, and then proceed to compare its capabilities 

 with other photo-lithographic methods. 



To prevent misconception, it may perhaps be well to state 

 that the manipulations I am about to describe are only such as 

 aid the lithographer in producing one particular kind of work, 

 namely that which is printed from smooth stones. My pro- 

 cess, in the form I shall give it in this paper, is chiefly 

 applicable to the reproduction of drawings formed of hard 

 defined lines, such as maps, pen and ink sketches, and im- 

 portant documents ; and less so to photographic views of 

 landscapes, portraits, or indian ink drawings, composed of 

 tints and shades ; and although the former class may not be 

 as interesting and attractive a study as the latter, yet I 

 believe it to be of equal, if not superior, practical value. 

 Circumstances have caused me to turn my attention more 

 particularly to the reproduction of maps and plans, and I 

 wish it to be understood that my remarks on this occasion 

 bear reference to that description of work. 



It is generally the case that the scale on which a map is 

 drawn by the surveyor of a district is very much larger than 

 that which would be wisely selected for publishing his map ; 

 inasmuch as the details become too minute and tedious, 

 and would take him more time than shoidd be expended 

 upon one copy, if he were to draw upon the usual publishing 

 size ; the consequence is that his plan must be reduced 

 before it is engraved or drawn upon stone. This process of 

 reduction is more or less troublesome as the map contains 

 more or less work, when it is accomplished in the old way; 

 but by photographic means it is a matter of the utmost 

 indifference whether the original be crowded or not. The 

 application of photography to reducing maps was introduced 

 into the Ordnance department of Great Britain, in the year 

 1855, by Colonel James, with perfect success. 



To proceed a step further, and imprint such a reduction 

 directly upon the stone in such a way that common litho- 

 graphs can be printed from it, is the problem the photo - 

 lithographer has to solve. 



