504 REVIEWS 
may lead to its being widely quoted by those not pretending to pass inde- 
pendent judgment upon the problem, that the following reply is written. 
In 1879 Professor George H. Darwin gave cogent reasons for thinking 
that originally the moon was much nearer to the earth than it is at present, 
and considered it probable that the earth and moon at one time consti- 
tuted a single mass, though this conclusion was admittedly in the nature 
of an inference from the preceding. As Professor Pickering states, this 
conclusion has been accepted by the great majority of astronomers, although 
many of the geologists do not view it with favor. Accepting this hypothesis 
as to the origin of the moon, the author states: 
When the Earth-Moon planet condensed from the original nebula, its denser 
materials collected at the lower levels, while the lighter ones were distributed 
with considerable uniformity over its surface. At the present day, we find the 
lighter materials missing from one hemisphere. The mean surface density of 
the continents is about 2.7. Their mean density is certainly greater. We find 
a large mass of material now up in the sky, which it is generally believed by 
astronomers formerly formed part of our Earth, and the density of this material, 
after some compression by its own gravity, we find to be 3.4, or not far from 
that of the missing continents. From this we conclude that this mass of material 
formerly covered that part of the Earth where the continents are lacking, and 
which is now occupied by the Pacific Ocean. In fact, there is no other place 
from which it could have come. 
Who it was that first suggested that the Moon originated in the Pacific. is 
unknown. The idea seems to be a very old one. The object of the present 
paper is to find what support for this hypothesis is afforded by the results of 
modern science, when examined both qualitatively and quantitatively. (P. 30.) 
All will agree that the hypothesis is a very interesting one and worthy 
of the space given to it, and, even if opposed by very strong objections, is 
still of value as a hypothesis in the absence of positive knowledge as to the 
age and ultimate origin of the ocean basins. It must be concluded, how- 
ever, as shown in these two paragraphs as well as many others in the article, 
that the author has not only failed to look up and to give credit to the 
originator of the hypothesis, which is here duplicated in many details, but 
has treated many phases of the subject with a positiveness and superficiality 
which cannot commend themselves to careful students of the subject. 
This is in marked contrast to the cautious treatment of the hypothesis by 
its originator, Osmund Fisher, in his initial statement of it entitled, “On 
the Physical Cause of the Ocean Basins,” Nature, Vol. XXV (1882), 
p- 243, or in his reprint of it as A Speculation on the Origin of Ocean Basins, 
chap. xxv, Physics of the Earth’s Crust, pp. 336-41, 379-81 (second 
edition, 1889). 
