344 RESEARCHES ON FUNGI 



i.e. the average force exerted by the inner peridium upon the pro- 

 jectile as it everts through a distance of 3 mm. is 0- 13 poundals or 

 0-004 lbs. 



(8) Rate of developing energy in the Sphaerobolus gun. In 

 calculating the horse power (rate of developing energy) of the 

 Sphaerobolus gun, let us consider again the case of the projectile 

 shot to the maximum height of 14-5 feet. As we saw under (6), 

 0.000037 foot pounds of energy are imparted to the projectile 

 before it leaves the gun ; and, as we saw under (2), this amount of 



energv must be imparted in second, i.e. the time taken for the 



&J r 1524 



inner peridial membrane to become everted. The imparting of 

 kinetic energy to the projectile therefore takes place at the rate of 



0- 000037 x 1524 = 0- 055 foot pounds per second. 

 Now one horse power = 550 foot pounds per second. If H.P. = 

 horse power, we have 



foot pounds per second 

 HP - = 550 



So that for our Sphaerobolus gun we have : 



0-055 1 



550 10,000 



i.e. the Sphaerobolus gun does work at the rate of one ten-thousandth 

 part of one horse power. 



(9) Summary of the calculations. 



Initial velocity of the projectile : 



if shot 7 feet high upwards of 21 feet per second ; 



if shot 14- 5 feet high . . . upwards of 30 feet per second. 

 Time taken for the projectile to reach its highest point : 



if shot 7 feet high upwards of 0-65 second ; 



if shot 14- 5 feet high . . . upwards of 0- 95 second. 

 Time taken in the discharge of the gun : 



1 



if it shoots the projectile 7 feet high about — — second ; 



lObb 



if it shoots the projectile 14 '5 feet high . . . about — — second. 



