394 
PRESTON. 
We may therefore assume that the density of the earth is 
1.77 times the density of the mountain, or that the 
Mean Density of the Earth == 1.77 X 2.90 = 5.13. 
The determination of the force of gravity at a point half 
way up the mountain gave a means of comparing the rela¬ 
tive densities of the upper and lower sections. The data 
for the three stations are: 
9’ 
Lat. 
h. 
Kawaihae. 
Dynes. 
978.8035 
o / 
20 02 N. 
Feet. 
8 
Kalaieha. 
978.4905 
19 42 
6,660 
13,060 
W:aiau. 
978.0599 
19 49 
A small correction for the wear of the knives is here 
omitted, being the same for all three stations. 
These values being corrected for their difference of latitude, 
and assuming the same value for A previously used, gives 
for the lower section a density nearly twice that of the 
upper. 
Conclusion . 
The work on Haleakala is entitled to more confidence 
than that on Mauna Kea, on account of the method em¬ 
ployed, but as the same densities of rock have been used in 
both cases we adopt the mean. The result of the work is 
then: 
Mean Density of Earth from Haleakala = 5.57 
“ “ “ “ Mauna Kea = 5.13 
Adopted mean.5.35 
The agreement of the two values is satisfactory when we 
consider that the methods were entirely different, the former 
depending on triangulation and astronomical latitudes and 
the latter on the diminution of the force of gravity from the 
sea level to the summit as revealed by the pendulum. 
