Journal of Agricultural Research 
Vol. V, Vo. 3 
118 
pan of the balance (fig. 2). The weight thus added opened the circuit, 
and a spring restored the block to its normal position, where the pocket 
was again filled by a ball from the reserve supply. Anderson did not 
Fig. i.—V esque's automatic balance for measuring transpiration. In this apparatus measured quantities 
of mercury are added to the receiver on the balance pan to counterbalance the transpiration losses. 
place the plant directly on the balance, but used his apparatus to register 
the gain in weight of absorption tubes connected with the transpiration 
chamber. He does not describe the form of the recording apparatus 
employed. 
Ganong (1905) in his “autographic transpirometer” (fig. 3) combined 
the ball-dropping and the recording mechanism in a compact and con- 
Fig. 2.—Anderson's apparatus for measuring transpiration, in which steel balls are used as weights. 
venient form, one electromagnet serving both purposes. Steel balls 
one-fourth of an inch in diameter were employed as weights. Balls of 
this size approximate 1 gm. each in weight. The clock was so arranged 
