108 



THE INDIA RUBBER WORLD 



[November 1, 1914. 



A New Form of Testing Device for Rubber. 



IN 1912 the French Society for Encoui menl of the National 

 [nduslrj oi Fra nferred on MM. C. Cheveneau and 



F. Heim a gold medal for the invention of a registering 

 dynamometei for testing rubber samples. 



Tins machine, as 

 can be seen by the 

 illustration No. 1, 

 herewith, re- 

 sembli s the Sch ipper 

 machine very closely, 

 bul lias a self-regis- 

 tering device, P, at- 

 tached to the arm 

 which c a r r i e s the 

 weight that swings on 

 a fulcrum, I i. By 



means i if a gear at O' 

 the cylinder revolves 

 as the weight is 

 raised By means of 

 the rack and pinion 

 V, which re- 

 v o 1 v e s a 

 smaller pin- 

 inn connect- 

 ed with the 

 chain beside 

 the cylinder, 

 and w h i c h 

 chain carries 

 a pencil, a 

 line is regis- 

 tered on the 

 c y 1 i n d e r. 

 The height 

 of the line 



Fig. No. 1. 



represents the stretch, and tlu distance of revolution shows the 

 ill or pull. 

 A great amount of complicated calculation has been given to 

 show the correctness of the registration. This is characteristic 

 of many continental scientists, who would rather make a compli- 

 cated calculation than a simple trial which would give a calibra- 

 tion, allowing for the numerous errors of the calculation and 

 compensating for any friction >r weight 6f the cylinder or mov- 

 ing machinery. 



At the International Rubber Congress held in London in 1911, 

 MM. Cheveneau and Heim gave an elaborate set of tables of the 

 tests made on this machine, but did not describe the machine. 

 It has not hitherto been illustrated, though it appears to have 

 merit. A criticism of the machine and of its system of operating 

 lias since appeared in France (Le Caoutchouc et la Gutta Percha; 

 July 15. 1914; page 8430), in which exception is taken to the 

 formulas and method of calculation. The anonymous author 

 suggests that instead of the foregoing apparatus, one be used 

 which is shown diagrammatically in figure No. 2. 



Here it will be seen that the pendulum P swings on the center 

 o, around which a cord extends to the sample a held between the 

 nippers. Attached to the nippers or holders are two pulleys 

 around which a cord is stretched attached to base at one end at f, 

 passing over pulleys at top and around wheel on end of register- 

 ing cylinder and finally ending in weight g. Now as the speci- 

 men stretches in the jaws it is evident that the weight g must 

 rise to twice the extent of the stretching of the sample. The 

 movement of the sample a caused by the swing of pendulum or 



J 



^"N -J 



HE:" 5 



weight I' will not have any effect on the length of this cord 

 which revolves the cylinder. Noi dot the weight oi g or fric- 

 tion of pulleys have anj influence, as this pull is transferred to 

 the weighl g through the grips on the sample a. 



The recording pen is 

 ni! ived by the bar d, a m- 

 nected with plate c, 

 which follows out the 

 extended end of pendu- 

 lum at b, thus following 

 the movements of the 

 weight and recording it. 

 1 hi weight e pulls the 

 pi ncil out through a 

 rack and pinion on the 

 bar d and the weight 

 pulley. It appears that 

 the pencil might be 

 moved by simple attach- 

 ment of cord from it to 

 wheel on center o, or at- 

 tached to ball c with the 

 same effect. A simpler 

 way would lie to have 

 the recording cylinder 

 attached to center o and 

 revolving with it. It 

 would be easy to so re- 

 arrange the cord be- 

 tween f and g as to 

 move the pencil instead 

 of revolving the cylinder, 



which would, of course, revolve with the shifting of weight P. 

 It is hoped that the above account of what has been done may 

 stimulate those who have the standard non-recording machines 

 of the same to attach a recording device such as an indicator 

 card cylinder machine like those used on steam engines. Of 

 course, rather than go into elaborate calculations, it is better 

 to merely calibrate by attaching standard weights or a series of 

 them in place of the sample a and noting the points at which 

 definite weights move the machine and the indicator cylinder. 

 Of course with this indicator or self-registering device hys- 

 teresis could be determined, as well as total strength, etc. 



The fullest data relating to the machine and experiments with 

 it may be found in the "Bulletin de la Societe D'Encouragement 

 pour 1' Industrie Nationale" Paris; Vol. 120, 113th year, No. 1, 

 p. 20, July, 1913. 



r 



Fig. No. 2. 



AMERICAN RUBBER BOOTS FOR THE ALLIES. 



Rubber boots of course come under the classification of 

 contraband of war, but inasmuch as the ocean steamers ply- 

 ing between English and American ports are not likely under 

 present conditions to be seriously disturbed, some American 

 manufacturers of footwear have evidently thought it quite safe 

 to ship rubber boots for the use of the allied armies. Four- 

 teen hundred cases — about 17,000 pairs — of short boots were 

 shipped from Boston on the "Scythian," sailing September 24, 

 an additional shipment of 10,000 pairs being made on the 

 "Arabic," sailing from the same port October 6, and a like 

 shipment leaving the next day also from the same port on 

 the "Bohemian." These shipments are probably only the 

 beginning of a large order for army use in the great European 

 combat. 



