A PPENDIX. ] DRA WINGS FOR PHO TO-ENGRA VI NG. 2 1 y 



in order that in the photo engraving they may be reduced in size, and thus lessen 

 the apparent imperfections of the drawings. The amount of reduction must be de- 

 termined by each individual, depending upon whether a fine and close or coarse 

 and broad style is natural. In the former case a reduction of % is sufficient ; in 

 the latter, % or even '/ z is desirable. The most generally useful reduction is found 

 to be '/ 3 *. 



If one knows the size of the page upon which the figure or plate is to be printed, 

 it is easy to plan exactly as to the size of the drawings. For example, a finished 

 plate is to be iox 16 cm., and the reduction is y£, then the drawing should be made 

 ■<2 larger than the plate ; that is, 15 x 24 cm. and ^ reduction will produce the ex- 

 act size needed. Then the enlarged page so determined can be outlined by the 

 T-square and the drawings artistically arranged in the space. If one does not 

 know at the outset the size of the page, the drawings may be made upon separate 

 papers, closely trimmed, arranged on card board, care being taken that they do 

 not overrun the limit of the page, as above determined, and pasted in position. 

 This is an exceedingly practical method of procedure, even when the size of the 

 page is known. Care should be taken to keep all straight lines representing per- 

 pendicular and horizontal directions upon the individual drawings, in correct rela- 

 tions to the corresponding outlines of the completed plate. For instance, the scale 

 of magnification (§ 177) should be parallel with the bottom of the page, and this is 

 easily determined by the T-square. 



\ 365. For mechanical drawings, the exact plan is carefully plotted, dots are 

 placed for intersections and endings of lines ; the Hues are lightly put in with a 

 sharp pointed, medium pencil, and then with a right-line pen and a circle pen. 



I 366. For a large natural history object, a blue print (§ 349) or a tracing made 

 from a camera {\ 350) is obtained ; or for a microscopic object, a camera lucida or 

 embryograph drawing is made (§ 176, 178). The outlines are carefully corrected 

 by comparison with the object, and sharply defined. The back of this photograph 

 or drawing is blackened with a soft lead pencil, and rubbed gently with a bit of 

 paper to make an even coating. To transfer the drawing it is placed over the 

 drawing paper and secured in the desired position with thumb tacks. All the out- 

 lines are then traced with an i\ory point, or a very hard, round pointed lead pen- 

 cil, and the outlines will appear on the drawing paper. These are again lightly 

 retouched with a pencil to complete defective lines. If it is desired to reverse a 

 drawing, as in the case of a tracing made with the camera ({S 350), it is placed 

 against a well lighted window pane, its outlines followed upon the back with a pen- 

 cil, and then its original outlines retraced with a soft pencil. It is placed face down 

 upon the drawing paper and the lines upon the back traced with a hard point, and 

 the outlines will be transferred to the drawing paper. 



A. If a diagram or outline drawing is desired, the outlines thus made are fol- 

 lowed by the pen, heavy, light, and interrupted lines being used to indicate differ- 

 ent classes of facts, according to the special need. 



B. If a shaded drawing is to be made, only those outlines are traced in ink which 

 indicate cut edges of tissue, or for some reason need to be emphasized in an espe- 

 cial manner. Then the shading is put in, the deep shadows and high lights being 

 strongly marked and the gradations carefully determined. This is more easily 



* In any case, the amount of reduction should be clearly indicated to the photo- 

 engraver. 



