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negatives contain objectionable features that it is not desirable 

 should appear in the iUustrations. When a drawing is prepar- 

 ed from the projection of such a negative, the objectionable 

 features can be omitted. Again, the desirable features of sev- 

 eral negatives can be combined and in this way results can be 

 procured which would be procurable in no other. As to the 

 details of the apparatus, little need be said so far as the pro- 

 jector itself is concerned. It is of the ordinary, pattern consist- 

 ing of an adjustible mirror capable of throwing the parallel rays 

 of sunlight through a large condensing lens. The cone of hght 

 produced in this manner is passed through the negative or 

 preparation and the light is brought to a focus on the screen by 

 means of an objective. This objective may be a simple cheap 

 meniscus, or may be a photographic lens, or a microscope 

 objective. All these forms are in use in the illustration- 

 room. It is more necessary to give the details of the screen up- 

 on which the projection is received and upon the surface of 

 which the artist produces his drawing. This screen is borne 

 between two uprights about seven feet high, set on four castors 

 placed sufficiently far apart to giye the apparatus a firm support. 

 After the apparatus has been rolled into position, four screw-legs 

 are screwed downward and the apparatus is thus raised off its 

 castors and placed on four legs, and is then sufficiently firm to 

 resist all the pressure that is brought to bear upon it. The 

 screen proper is pivoted between the two tall uprights, and 

 by means of a series of notches is adjustable in the vertical 

 direction. The screen consists, to all intents and purposes, 

 of a very large glazed window sash having the glass flush 

 with the framework. The sides of this sash or frame are 

 sufficiently strong to give it firmness and when the nece's- 

 sary angle is secured, a pair of clamps secures the screen 

 from any mal-adjustment. At each end of the screen, two long 

 pieces are hinged in such a way as to facilitate the manipulation 

 of the paper upon which the artist works. These long narrow 

 pieces are four feet long and one inch square and are hinged at 

 the top of the screen and pass downward everywhere equi- 

 distant from the side of the frame, this distance being about 

 three-fourths of an inch. At the lower end, these pieces are con- 

 stantly pulled inward or toward the glass, by spiral springs. The 

 under surface of each of these long pieces is lined with sand- 

 paper. If now a long soft wooden stick suitable for the attach- 

 ment of drawing paper be placed across the glass face of the 

 screen, which as before remarked is flush with the frame, and 

 be passed under the sand-paper surfaces, these latter will grip it 

 with great firmness, and it will be found impossible to move it 



