392 
PRESTON. 
more than that at the summit of Green Mountain reduced 
for elevation, indicating that the downward attraction of all 
matter above the sea level was insignificant.* In order to 
determine the density of Mauna Kea, an extensive collec¬ 
tion of rocks, was made at different stations, beginning at 
Kawaihae on the leeward side, passing to the summit, and 
finally ending at Hilo, on the windward side. In all, 26 
specimens were obtained. They have been carefully studied 
by Professor G. P. Merrill, Curator of Lithology at the 
Smithsonian Institution, who has kindly furnished the fol¬ 
lowing densities. The points from which they w T ere ob¬ 
tained are indicated in Plate 10 by numbers and letters. 
Only 18 determinations were made, as this number seemed 
to include all the distinct types in the collection. 
Density of Bocks on Mauna Kea. 
Density. 
Remarks. 
No. 
Density. 
Remarks. 
2.82 
13. 
2.00 
3.08 
14. 
2.73 
2.90 
16. 
3.02 
In powder. 
2.90 
16. 
2.99 
In bulk. 
2.79 
17. 
2.73 
2.76 
18. 
2.83 
2.84 
D. 
2.88 
2.27 
In powder. 
23. 
2.80 
2.12 
In bulk. 
23. 
1.70 
Scarce. 
The mean of the above values is 2.68. This, according to 
Professor Merrill, may be slightly under the true value. A 
specimen from the Island of Hawaii not included in the 
above collection gave a value of 3.20. In Professor E. S. 
Dana’s “ Contributions to the Petrography of the Sandwich 
Islands” in the American Journal of Science, June, 1889, the 
results of a number of determinations of specific gravity are 
given from the same island. Seven specimens of basalt gave 
values ranging from 2.82 to 3.00 (p. 442). Another group 
of seven determinations furnished examples of even heavier 
lava, ranging from 3.00 to 3.20 (p. 447). If we take the 
* Royal Astronomical Society. Memoirs. 4°. London , 1834, vol. 7, p. 60. 
