24 



to meet the requirements of the case. It is very desirable to 

 fully control the illumination. Sometimes the object has to be 

 strongly illuminated, and the drawing-board weakly illuminated; 

 sometimes the reverse is the case, the object has to be weakly 

 illuminated while the drawing board has to be very strongly 

 illuminated, and the variation in illumination should be as great 

 as possible,'— from strong sunlight to absolute darkness, if pos- 

 sible. This is the main point in the successful use of the camera 

 lucid'a for this class of work. This object is attained in the 

 present piece of apparatus by placing the whole at a sunny 

 window and modifying the light by a series of seven roller blinds. 

 One of these, and one of the most important, is the blind at- 

 tached to the window itself. This does not differ from those 

 elsewhere described in this report. The other bhnds for this 

 piece of apparatus have the peculiarity of working in the hori- 

 zontal direction, the rollers being placed vertically side by side 

 and enclosed in a light-tight box at the side of the window. The 

 box on the right carries three of these rollers and that on the 

 left carries a corresponding set of three. These blinds are of 

 varying nature. One of each set is white, another is nearly 

 translucent and a third is somewhat opaque. By placing these 

 blinds one over the other, that is by adjusting them properly in 

 the horizontal direction, the light may be varied to any extent 

 required. No way has yet been found by which the light both 

 upon the object and upon the drawing board can be fully con- 

 trolled by foot-power, as in the case of the microscope window 

 previously described; but it is believed that if sufficient thought 

 were given to the subject, such a device might be evolved. In 

 the meantime, the present arrangement works fairly satisfac- . 

 torily and avoids the use of complicated apparatus between the 

 eye and what it is looking at, in the same way as does the appar- 

 atus previously described in connection with the microscope 

 window. 



A LIBERAL REDUCTION OF ORIGINAL DRAWINGS. 



A study of the published work of the best modern artists gives 

 ample proof that their originals are considerably reduced foi 

 purposes of publication. From the examination of the published 

 illustrations it is difficult to give an estimate of the amount 

 of reduction that takes place in the process of photographing 

 the original, but a somewhat extensive and careful study of the 

 best modern magazine illustrations leads to the conclusion that 

 in many cases the reduction is a liberal one. Judging from the 

 texture of the drawing as s^hown in enlarged projections, it is 

 probably not far from correct to say that the reduction varies 



