162 



the alH.ve. Credit is due Mr. il. P. HoUbs for His assistance in devising 

 the nicelianical parts. 



FROG TABLES. 



These tables are modifications of those used in the University of 

 Pennsylvania, and meet certain requirements better. They consist, Figure 

 6 of a brass plate 4yo"x8", to which is glued a single piece of cork i/o" 

 thick, and the adjustable arm or support. The adjustable part consists 

 of a brass block (c) which slides upon the s.iuare rod (e), the set-screw (b), 

 and has a horizontal play of 4%". The set-screw (a) allows of a further 

 circular movement of the plate, and the s.iuare supporting arm is held to 

 the stand l»y a nniversal clamp. , 



^A^^^tc^bVe 51^-^. 



