:.L' IT.',. 



Friction, Elasticity. 



303 



52161. 1:10. 



52 167. 1 : 8. 



52166. 1:12. 



52 168. 1 : 6. 



52 169. 1 : 7. 



52.163. Percussion Apparatus, Figure, with 5 balls of the same size and 3 of different s. <l. 

 sizes, of lignum vitae, the ratio of weights of the latter balls being 1 / 2 : 1 : 2 ... 1. 16. 



52.164. - - idem, with ivory balls, Figure (the balls of equal size being 35 mm diameter) 4. 16. 

 5i', 165. Percussion Apparatus, Figure, with 7 ivory and 3 lead balls 25 mm in diameter 2.14.0 



51'. 166. --idem, Figure, with 6 ivory and 6 lead balls 25 mm, and 1 ivory and 1 lead 



ball 30 mm in diameter, and comparison scale 3. 0. 



52.167. Apparatus, Figure, for showing that the angle of reflection is equal to the angle 



of incidence, with ivory ball (Fr. phys. Techn. I, 2, Fig. 3303) 2.10.0 



52.168. -- idem (Frick's) (Fr. phys. Techn. I, 2, Fig. 3302 [I, Fig. 442]), Figure .. 0.16.0 



5i'. 169. -- idem (Nollet's), with ivory ball falling perpendicularly, Figure (Fr. phys. 



Techn. I, 2, Fig. 3304) 2. 10. 



51'. 170. Glass Spiral of thin Glass Fibre, for proving elasticity, in preserving tube (W. D., 



p. 139) 0. 1.0 



52.171. Glass Vessel, cracked spiral shape, Figure, for experiments in elasticity ... 0. 3.0 



The flask forms a largo, closed, spring spiral, and can be taken apart. 



52.172. Rubber Hose for Elasticity Experiments (W. D., p. 139 [118]), 40 cm long, with strong 



hooks on the ends 0. 5. 



52. 173. Apparatus for demonstrating and measuring the expansion and elasticity of wires of 

 different metals, by extension and heat (Fr. phys. Techn. I, 2, Fig. 3244) 3.10.0 



52. 174. Wood Rod for experiments on elasticity in bending (Friedr. C. G. Mailer's) (M. T., 



p. 50) 0. 2.0 



52.175. Apparatus (S'Gravesande's), for showing the elasticity of metal wires (M. P. I, Fig. 328 



[320]) 1. 2.0 



(1. 



ll>, !>TTO, 



