LIFE IN THE INFRA-WORLD 31 



sive impulses through the feet to the brain if they 

 are to be adequately and suitably dealt with. It is 

 just like a mercantile office in which the staff can 

 only do business at a definite rate. This interesting 

 physiological fact is illustrated by the coalescence of 

 separate air-pulses into one continuous note if they 

 exceed 40 pulses per second, and the similar coales- 

 cence of flickering images. The " central exchange " 

 of the human machine is only constructed for some 

 40 exchanges per second, and it is easy to calculate 

 that the normal span of human life contains about 

 10 11 such impulses. This figure, recurring as it does 

 again and again in our calculations, seems to be 

 of a significance hitherto little realised. Its close 

 proximity to the figure expressing the velocity of 

 light in centimetres per second (3 x 10 10 ) is mis- 

 leading, since that figure changes with the units 

 of length and time. But another significance may 

 attach to it independent of the units. It certainly 

 is the ratio of the speed of light to the average 

 speed of animal locomotion. 



If this figure of 10 11 (a hundred thousand million) 

 he allotted number of nerve-impulses for all 

 sentient beings, it follows at once that longevity 

 must be proportional to length. And if this is 

 true in the infra- world, tho normal span of lite 

 will be reduced 10 22 times/' in the same ratio 

 as space and time. Seventy infra-years will there- 

 fore be tho normal span of life of the infra man. 



