458 
Journal of Agricultural Research 
Vol. XXXI, No. i 
upward pull on the fine piano wire fastened to the rib a few inches 
from its emergence from the bud gave a direct index of the growth 
being made. A piece of coiled wire tubing fastened rigidly to the 
palm trunk below the record leaf and to the side of the clock case 
served as a conduit for the piano wire between its attachments to 
the leaf and to the pen-carriage. The pen-carriage traveled on two 
parallel horizontal guide rods, and the beginning of a record was 
placed at the left hand or distal end of the cylinder. The pull of the 
wire to the right in response to the growth was counterpoised by a 
small rubber band on the left, giving a positive and steady motion 
to the pen. At the same time the position of the band was adjusted 
to regulate the pen pressure on the record cylinder. 
Although this mechanism develops some friction on the wire, and is 
lacking in the extreme delicacy usually essential to an auxanometer, 
the strong up-push of the growing date leaf and the rigidity of the rib 
probably compensated for these features; and the general stability 
of this device was a positive advantage in out-of-door conditions, with 
almost constant high winds to be withstood. It is obvious that with 
this arrangement the pen traces a smooth line around the cylinder 
and parallel with the base when no growth is made, while growth is 
recorded by a slowly advancing spiral. As the circumference of the 
Fig. 1.—A.uxan3tn3ter record of growth of date-palm leaf at the Government Date Garden, Indio, Calif., 
May, 1918 
cylinder, making one revolution in six hours, is 12 inches, the cylinder 
must rotate past the pen one-sixth of 12 inches or 2 inches in one hour. 
Hence each five-minute period would be represented bv one-twelfth 
of 2 inches or one-sixth of an inch on the circumference of the cylinder; 
while the longitudinal progress of the pen on the cylinder, actuated by 
the pull on the piano wire, would record the actual growth made. 
This secures a fairly accurate recording of the beginning and ending 
of the growth periods, as well as a comparison of the growth rate 
during the different periods of the night. 
When no day growth is made the pen does not advance and the 
pen-trace runs around the cylinder as a single line parallel to the 
cylinder heads at the point where growth ceased. 
Between sunrise, when growth ceases, and sunset, when growth 
is resumed, the cylinder would make nearly two complete revolutions 
with the pen tracing the same mark. 
Table I shows the daily growth, in millimeters, before and after 
midnight, with the time of beginning and ending from April 24 to 
May 20, inclusive. Figure 1 reproduces a tracing from one of the 
record sheets, most typical of three days’ growth. (One should 
imagine this wrapped around the cylinder, with c and d contiguous 
and revolving in the direction of the arrow A.) 
The horizontal lines c-d, e-f, and g-h show two revolutions of the 
drum during sunlight without registering growth. The heavy lines 
