Manchester Memoirs, Vol. Iv. (191 1), A^^. 1*^. 7 



XZS 



Fig. 2. Joule's Results. 

 Rubber -j^" .si]uaie. Not vulcanised. 



o 'o to 30 ■«» 



Fig. 3. Joule's Results. 

 Vulcanised Rubber. Section |" square. 1,452 grains per foot. 



