rg1r] TRANSEAU—APPARATUS FOR TRANSPIRATION 55 
and irrigators. Of these the chronograph, the weight droppers, 
and the irrigators are new forms of well-known devices. 
THE CHRONOGRAPH.—Where synchronous records are desired, 
it seemed that a chronograph having several pens to mark on the 
same sheet of paper would be more desirable than several separate 
instruments, not only on account of the decreased cost, but also 
Fic. 1.—Complete apparatus for recording comparative transpiration data: 1, 
combined hygrograph and thermograph; 2, weight dropper; 6, irrigator; 7, chrono- 
graph. 
because the errors of the clocks would be eliminated. The chrono- 
graph shown in fig. 1 has an eight-day movement attached to a 
horizontal cylinder 15 cm. long and 15 cm. indiameter. The record 
is made by pens which mark a continuous line except when drawn 
aside by an electro-magnet. At present the instrument bears four 
pens, but it is so constructed that four more may be added on the 
same side, thus increasing its capacity to eight synchronous records. 
By lengthening and shortening the hairspring the space traversed 
by the pen in one hour may be varied from 2 to 5 mm. In the 
