766 
PROFESSOR 0. REYNOLDS ON CERTAIN DIMENSIONAL 
This variation in the comparative times for air and hydrogen is strictly in accordance 
with Law VI., Art. 9, as is also the manner of variation, as the pressure falls, of the 
times for each particular gas. These variations indicate that there are certain pressures 
for the stucco plate corresponding with certain other pressures for the meerschaum, at 
which the relation between the times for hydrogen and air are equal, and the variation 
of these times with the pressure similar. 
Logarithmic homologues. 
40. To test this, the logarithms of the pressures and times are plotted, and curves 
drawn, as explained in Art. 28. These are shown in fig. 8. 
Fig. 8. 
02 
5 
O 
o 
o 
03 
O 
‘-3 
03 
a 
-4-3 
Cm 
O 
03 
03 
.s 
a h and c cl are the curves for air and hydrogen through meerschaum, e /‘and g h are 
the curves for air and hydrogen through stucco. The figure consisting of the two 
curves e f and g h is found to fit on to the figure consisting of a h and c d, the displace¬ 
ment being from ef and g h to e f g' li. The scale of the figure is too small to allow 
of the position of the points marking the experiments being shown, but these are 
shown in the larger figure, diagram 1, Plate 47. 
The agreement is there seen to be very close—the very considerable portions of the 
curves which overlap coming into actual coincidence. 
