2 1 8 DRA WINGS FOR PHO TO-ENGRA VING. [ APPENDIX. 



done if a pencil or wash drawing is first made. The shading may either he done 

 by dotting the surface with a pen (stipple) or by lines. It is much easier to pro- 

 duce acceptable results by stippling, because a slight erasure may be made or a 

 deeper shadow obtained by adding a few carefully placed dots. This method is 

 well adapted for showing the structure of histological specimens. 



C. If lines are to be used for shading, the beginner will find it more satisfactory 

 to use the fine lithographic pen, the line extending from the shadow toward the 

 high light and ending in a series of dots. The deeper shadow is reinforced by a 

 second or even third series of lines, and these should rarely cross each other at 

 right angles. They should rather follow the contour of the surface represented 

 and in crossing should form diamond shaped spaces. A study of good copper or 

 steel engravings will aid one in securing a proper method and instances of excel- 

 lent pen work abound in the first-class illustrated magazines from which valuable 

 suggestions can be obtained 



D. It is sometimes desirable to be able to put white lines ever a dark shadow. 

 In this case a white ink may be used. 



E. Occasionally a very dark picture is needed. In this ca^e a specially prepared 

 paper may be used and covered with an even wash of black ink. Lines are cut 

 out with a sharp instrument, thus leaving white lines on a black background. 



F. Paper with a raised stipple is sometimes used. Upon this the shading is done 

 by wax crayons, the crayon adhering to the elevations and leaving the depressions 

 white. Lines and deep shadows are put in with ink. In this way more excellent 

 drawings can be made than by the more laborious method with pen and ink, but 

 as a rule the results of the photo engraving are not so satisfactory. 



G. In case it is necessar}' to show different colors, the drawing is made in dif- 

 ferent colored inks exactly as desired, pale colors being avoided. The photo en- 

 graver makes a plate for each color, and the accuracy necessary in their production 

 and printing makes the process many times more expensive than the simple repro- 

 duction of a black and white drawing. 



\ 367. Lettering. — A half-tone engraving from a photograph may have letters 

 placed upou it by a second printing. 



The most carefully prepared drawing may be artistically ruined by placing upon 

 it ill-formed and irregular lettering, and as even, artistic lettering is almost a trade 

 by itself, it is recommended that either the drawing be sent to the photo-engraver 

 with directions to have the letters properly put in, or what is more satisfactory, to 

 have the letters, abbreviations and words needed, printed and separately placed on 

 the drawings. 



To do this, type of the proper size for the reduciou determined upou is chosen. 

 Numbers of the following size have been found convenient for numbering the 

 separate figures of a plate for ' 3 reduction ; 



60, 61, 62. 



of the following size for serial parts of the individual drawings, 

 1, ' 2, 3, 4, 5, 



while italic letters of the following size show what has proved most satisfactory for 

 ]A, reduction, 



