2S 



Fig. 4. Sketch 

 of the arrangement 

 of a camera lucida 

 for the production 

 of drawings of ob- 

 jects at nearly the 

 natural size. The 

 apparatus is at- 

 tached to upright 

 steel girders, one 

 at each side of a 

 window. The artist 

 faces the light. 1, 

 2, the two steel gir- 

 ders which 

 are imbed- 

 ded in sev- 

 eral tons of 

 cement be- 

 neath the 

 building and 



pass through the floor without contact; 3, cross-piece to carry 'an or- 

 dinary camera (4), this cross-piece being hung on sash weights and sliding 

 in the vertical direction and readily clamped by the side screws shown; 4, ordinary 

 camera pushed up out of the way but easily brought into use as shown in Fig. 4; 

 5, anti-friction arms of the cross-piece (3) which roll against the edges of the 

 girders 1^ 2; 6, left hand box of roller blinds; 7, right hand box of roller blinds; 

 8, liffht-tight vertically acting rollerblind of the window; 9, 10, horizontally act- 

 ing roller blinds from the boxes 6, 7; 11, object to be drawn, held in stage forceps; 

 12, mirror of ordinary camera lucida; 13, horizontal stage, adjustable in the ver- 

 tical direction, designed to support the object 11, which in this case is supported 

 on the stage of a microscope carrying no objective or eyepiece; 14, horizontal 

 stage, adjustable in the vertical direction, designed to support the drawing board, 

 which tips out to pass 13, and is also adjustable in the horizontal direction. 15, 16, 

 framework supporting all the apparatus 6-14 and slung on sash weights so as to 

 be easily pushed up out of the way when the window is used for other purposes; 

 17, screw clamp to stage 14; 18, roller blind acting as a light trap and diaphragm 

 when the window is used with the solar r)rojector as shown in Fig. 2. 



