tort] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 431 
1.76+1.62, or 1.09. Each pair of coordinate coefficients for each 
test is averaged, also, in the table. 
TABLE III 
CORRECTION COEFFICIENTS 
Brown atmom. | Black atmom. | White atmom. 
Physal. Xanth. | Physal. | Xanth. | Physal. Xanth. 
Ist sun exp...|. 0:86 0.85 1.09 1.08 t.66 233 
Test I | 2d sun exp....| 1.58 ©.99 r.74 1.09 1.50 1.46 
Average..... 122 0.92 1.42 I.09 60° 7 3290 
Ist sunexp...} 1.69 0.76 1.99 0.90 T.99 2.90 
Test II | 2d sun exp....| 1.12 0.70 1.29 0.80 59% 0.75 
Average ..... 1.40 | 0.73 1.64 | ©. 85 | 1. 0.83 
The second series of observation (test III) was carried out from 
10:00 A.M. to r:00 P.M., August 11. The shade here used was of 
two thicknesses of cheesecloth. Three plants were used, one of 
each of the forms above mentioned, but different specimens, and 
one of Martynia louisiana. Besides the three atmometers, all 
of our other instruments were operated in this series. We may 
neglect the losses for the first half-hour periods of each exposure, 
since they are not to be used in calculating the different ratios. 
The rates of loss, or in the case of non-evaporating instruments the 
averages of two readings taken at the beginning and end of the ~ 
Second half-hour of each exposure, are given in table IV, and 
the corresponding coefficients of correction in table V. There was 
almost no discrepancy shown between the first and second readings 
of the non-evaporating instruments; the conditions for the half-hour 
Were sensibly constant. In the case of the two photographic papers 
the ratios are of course inverted, since the light intensity must vary 
inversely as the time required to produce the given depth of color. 
A third series (test IV) was carried out on August 12, from 10:00 
A.M. to 1:00 P.M. The plants were similar to those of test III, but 
were different individuals; the shade was of canvas, as in test 1, 
For this series only the final coefficients of correction and their 
averages need be given. They may be found in table VI. 
