10 Mr. A. G. Levy. On the Elasticity of the Living 



If, however, the pressure be kept up for only two to five seconds the 

 recoil is more perfect. In fact, the immediate recoil which takes place 

 in the first two or three seconds may give a ratio of 1/2 or even 1/1*5 ; 

 after an interval of thirty seconds or so it may be 1/1'4 or even 

 nearly 1. E.g., Experiment 12a = 1/1'2 (fig. 5), Experiment 14a 

 = 1/T5 (immediate). 



Fia. 5. 

 Time in Seconds. 



On4" 10 " 20" 30" 40" 60* 



If the pressure be prolonged, say, for six minutes, the fraction be- 

 comes smaller, and this is shown in fig. 6, where the ratio = l/2'74, 

 and the surface does not further recover after a long interval more 

 than half an hour. 



Thus we see that although the elastic reaction of the brain is very 

 fair when the compression lasts only a few seconds, longer compres- 

 sion affects the brain in such a fashion that it does not recover so 

 readily. 



Thus, also, we see that for the same weight and same length of 

 compression, the elasticity is very much the same in different brains ; 

 i.e., with a large excursion there is a proportionately large recoil, and 

 vice versa. 



iii. Results of Experiments with varying Weights. A few experi- 

 ments performed with a weight of 20 grams show a comparatively 

 small excursion, but the ratio is similar to that obtained with a 

 50 grams weight. Weights such as 100 grams and over seem to be 



