393 



under observation had been transcribed in the manner shown in Table 11 

 and were now plotted for each group of pupae on the equal-velocity 

 chart as shown in Figs. IT, 19, 21, and 22. The dots lying between the 

 lines which separate the even 5-velocity units were taken together, and 

 the temperatures of the groups averaged together, the velocities averaged 

 together, and humidities averaged together. For example, the averages 

 for the interval between velocity 5 and velocity 10 in Fig. IT are shown 

 at the right as follows: N, number of readings, is TT ; H, mean humidity, 

 is 63.(5; T. mean temperature, is 57. 9; V, mean velocity, is 7. These 

 mean velocities were then plotted on the mean temperatures as shown in 

 Fig, 18. where velocitj- 7 will be found plotted on temperature 57.9°, and 

 all other plotted points corresponding to the figures in the margin of 

 Fijr. 17. 



87 88 -r 



Pig. 18. Curve drawn through the mean velocities (crossed circles) and 

 temperatures shown at the right of Fig. 17. The corrections applied to the 

 actual temperatures are shown in the insets at the corners of tne figure. Fol- 

 low the dotted line and arrows from 57° to 59° F. The actual threshold was 

 estimated to be 45° and the alpha value to be 52.3°. The substitution-quotient 

 was 270. 



A curve was next drawn through the points plotted in Fig. 18. The 

 temperatures not on the straight line were dropped out and the tempera- 

 tures with the same velocity on the straight line were substituted by the 

 method explained on p. 387. To use this method, take for example, 

 temperature 57° F., on Fig, 18, run up to the velocity curve, over to the 

 straight-line extension, then downward as indicated by the arrow, and 

 note that 59° F, is the temperature to be substituted for 57° F. The 

 equal-velocitv equivalents of all the temperatures not on the straight line 



