Oct. 18,1915 
Automatic Transpiration Scale 
125 
Spring motor for raising beam. —The dropping of a ball into the 
receiver is ordinarily sufficient to raise the opposite end of the beam 
and open the circuit. It sometimes happens, however, when the trans¬ 
piration rate is high and a gusty wind is blowing, that the beam remains 
down until the transpiration has been sufficient to require a second ball 
Fig. 11.—View of the beam and auxiliary equipment of the platform transpiration scale designed to carry 
large pots of plants weighing 150 kgm. or more. As the plant loses weight, the beam falls and the plat¬ 
inum point P closes a circuit through the mercury cup U. This actuates the ball dropper A, which 
deposits a ball in the receiver L. At the same time the cam K makes one revolution, raising the beam 
to its upper position and leaving it free to fall. An oil dashpot is provided at O. 
to counterbalance the loss in weight. Under such conditions the balance 
would fail to operate without the intervention of some protective device. 
This protection is secured by a spring motor which raises the beam to 
its upper position each time a ball is dropped and then leaves the beam 
free. The motor, which consists of a strong 8-day clock movement 
equipped with a fan, F (fig. 14), to reduce the speed, is controlled by 
