102 T. C. Mendenhall—Force of Gravity 
Time on Summit—temperature, 8°°5 ; barometer, 19°5 inches ; 
Z,—=1°000146 
Correction for temperature 
to reduce to 23°95 . . . °000140 
Ait GoMrection Oo Ps 000050 
‘ime reduced to Tokio conditions. 
Assuming the value of the force of gravity at Tokio to be 
as previously determined, 
9 ,=9°7984 
it follows that on the summit of Fujiyama, 
9,=9°7886 
Mr. Peirce has introduced an important correction to the time 
of vibration of a pendulum which depends upon the flexure of 
amount of flexure was possible. . 
The question at once suggests itself, whether it is possible to 
make use of this result in a determination of the density of the 
earth. While many of the circumstances are extremely tavor- 
able to this end, many of the data are, unfortunately, quite uncer- 
tain. It was originally planned to undertake at the same time @ 
complete trigonometrical survey of the mountain, in order to ob- 
tain the necessary data as accurately as possible. This, however, 
we were obliged to defer, but it is hoped that it may be made 
at some future time. The following is offered as, perhaps, the 
nearest solution of the problem possible under the circum: 
stances. 
Fujiyama is an extinct voleano, whose height is known to be 
2:35 miles very closely. It is renowned for its almost perfect sym- 
metry of form, and for the fact that it rises solitary and alone 
out of a plain of considerable extent. Thus there is not much 
to consider except the attraction of the mountain itself. To 
determine this is, of course, a matter of considerable difficulty. 
but it is believed that a result not far out of the way is reac 
by making the following assumptions. Without any great error 
the mountain may be assumed to be a cone. The summit angle 
of this cone has been obtained by making careful measurements 
upon a large number of photographs of the mountain, taken 
from many different points of view. The mean of many 
measurements, which do not differ greatly among themselves, 
gives for this angle 138°. Another point of vital importance 
is the mean density of’ the mountain. The rock, as far as cat 
