296 MEASUREMENT OF HIGH TEMPERATURES. Ibull. 54. 
96, which contains data for the smallest radius occurring in the present 
work, 22=0.0079 cm , it appears that the value of rj increases very perl 
ceptibly as P—p increases. The different lines drawn correspond toi 
differences in bore of the readjusted tubes. At 9.80°, owing to thq 
length of time of a single observation, only one datum is at hand. 
Turning thence to Table 97, which holds for tubes of a larger borej 
(i2=0.0184 cm ), the values ?j 4 77100 . . . are found to lie on very nearly 
straight lines, which, in comparison with those of the preceding table, 
have increased enormously in obliqueness ; 77 therefore increases at a 
rapid rate with P—p, which rate, however, diminishes as temperature 
increases, and is nearly zero at 1025°. Now, iuas'much as the rate 
of axial transpiration decreases with temperature, and inasmuch as 
Meyer's formula fails for values of the velocity of the particles above a 
certain datum, these curves suggest that the observed decrement of 
slope of the lines produced by temperature is due to the decrease of 
the axial velocity of the transpiring particles produced by the same 
cause. In this place the differential results of Table 103 are available, 
and furnish data for 77 625 . The values for t/ 975 , which Table 103 also con- 
tains, are, in general, in good accordance with the data of Table 97, 
and are therefore not essential to the diagram. 
Tables 98, 99, and 100 contain results for the largest value of radius, 
i2=0.027 cm , occurring in these experiments. In Table 98 the results 775, 
7ui 7ioo» show a tendency to curvilinear loci. But the true character of 
the phenomenon appears none the less clearly. The mean rate of 
increase of 7/ with P—p is distinctly larger than in the previous instance 
(Table 97). Again the slope decreases as temperature increases, and 
is practically zero at 930°. Here, therefore, the effect of the axial 
velocity of the transpiring particles is again apparent. 
Table 99 is more full as regards the sequence of data contained, as 
well as more accurate ; 7/4 shows a tendency to curvature, but the points 
may serviceably be grouped on a straight line ; t/ 676 is the mean of the 
first set of results for tempsratures of the Argand air-bath. Inasmuch 
as pressures are high and low alternately in both this series and the 
next, the line connecting corresponding observations has fair claims to 
accuracy. The data substantiate the inferences drawn with reference 
to Table 88. The lines are all oblique and they approach horizontality 
in proportion as higher temperatures are reached. 
I may notice here that in case of high temperatures the cooling effect 
of air passing through the capillary under high pressure was very dis- 
tinctly discernible, the thermo-couple showing differences of 20° to 40° 
between the maximum and minimum rates of flow. 
Table 100 finally contains results of my largest radius, jR>0.027 cm , the 
exact value of which I do not now care to measure, because the capillary 
apparatus has been carefully put together and all mercury manipula- 
tions involve danger. In this emergency I made the permissible sup- 
position that for P— i>=0, the value of 7/« is the same as that in Tables 
(950) 
