300 



Mechanics of Solids (Statics and Dynamics). 



No. :.:M!L' 



52 144 A. 1:9. 



52 144 B. 1 : 5. 



52,142. Resonance Apparatus, as suggested by Prof. Bug. Meyer, for demonstrating torsional 

 vibrations of elastic waves by resonance (Z. d. V. d. I., 53, 1909, p. 1301 et seq., No. 19, 



and text-sheet 16, Fig. 50) 



i. S. (1. 



6. 15. 



52,143. Analysing Apparatus for vibrations, as suggested by Grimsehl, for analysing the vibra- 

 tions of tuning forks, strings, etc., and for determining the frequency of sirens, He. by 

 a photographic method (Ztschr. f. d. phys. u. chem. U., 17, 1904, p. 33) 1. 



8.0 



52,144. Apparatus for Cavendish's Experiment on the Attraction of Mass (Gravitation Balance), 

 as suggested by Boys, F i g s. A and B (Ztschr. f. d. phys. u. chem. U., 14, 1901, p. 381; 

 M. T., p. 86) 15. o.(t 



Two small silver balls, each 0.75 g in weight, are suspended by means of a very fine quartz fibre 

 from a fine balance beam (torsion balance). The whole is enclosed in a glass case and has a firsi rate 

 arrestment device so that the instrument can be carried about from one place to another without fear 

 of damage. The small balls are influenced by large lead balls each 2800 grams in -weight which can be 

 moved along a frame to the two end positions by cords. In order to make the deflections visible to 

 a large audience, an image of the filament of a glow lamp is produced on a scale fixed to the wall 

 by the aid of a bi-convex lens and a light mirror fixed on tin apparatus. 



To give an idea of the sensitiveness of I lie apparatus, we might mention that an apparatus 

 installed in our test room gave a preliminary deflection of ' s of the scale distance in one direction 

 when the lead balls were moved from the centre to one of the end positions; alter some movement to 

 and fro of the balls the luminous pointer stopped at about 21 cm to the left or right according to 

 the direction of movement of the balls. The scale distance in this case was only 2.25 m. -- Com- 

 plete directions for use are given with each apparatus. 



.M-M45. Attraction of Mass Apparatus, Wrinhold's (\V. I)., -l<" Kdn., Fi<r. 100) 17.10.0 



ci. :<: 



