294 



COMBINED PROJECTION 



[CH. IX 



table 



8 b 2 



(yip 



b3 



c w (t) 



Base Board 



Fu;. 159. HOME-MADE OPTICAL BENCH KOR ALL PURPOSES. 



Base Board This is drawn at the right as if transparent to show the track 

 and under side of the carrying 1 flocks, and the various ways in which the guid- 

 ing cleats can be applied. 



t t t t The tubular tracks on which the carrying blocks ride. 



