74 REVIEWS 
into the real inquiry, related solely to the distribution of gravity, they 
have been associated by the authors with ideas of rigidity and isostasy, 
the purpose of this undoubtedly being to give to the inquiry a definite 
relation to geophysical problems. While this purpose is eminently laud- 
able, it is not clear to the reviewer that this particular association with 
questions of rigidity and isostasy is altogether happy, as will be indicated 
later. These terms will therefore be omitted from the following state- 
ment of the hypotheses on which the trial solutions were based, though 
the term ‘‘isostatic compensation”? will be retained as a convenient expres- 
sion of gravitative equilibrium reached by variation in density. 
Five trial solutions by the method of the least squares were made 
on the basis of five hypotheses of the distribution of density, as follows: 
Solution A was based on the assumption that there is a complete isostatic 
compensation at the depth zero beneath the ocean floor; that there exists 
immediately below every elevation a defect of density fully compensating 
for the elevation, and that at the very surface of the ocean floor there lies 
material of the excessive density necessary to compensate for the depres- 
sion of this floor. 
Solution B was made on the assumption that the portions of the con- 
tinent above the sea-level are excesses of mass, and that the oceans repre- 
sent deficiencies of mass, and that no isostatic compensation exists; or, 
in other words, the solution was based upon the supposition that, if iso- 
static compensation exists, it is uniformly distributed through an indefinite 
depth. 
Solution E was made on the assumption that isostatic compensation 
is complete and uniformly distributed throughout a depth of 162.2 kilo- 
meters. 
Solutions H and G were of the same type as E, but based on the 
assumptions that the depths of compensation are 120.9 and 113.7 
kilometers respectively. 
The sums of the squares of the residuals of these different solutions 
were as follows: 
Solution A, depth of compensation zero) 52". nee) 2 13,937, 
Solution B, depth of compensation infinity . . . . . . 65,104 
Solution E, depth of compensation 162.2 kilometers . . . 8,174 
Solution H, depth of compensation 1207 Oukilometers eae) 67,087, 
Solution G, depth of compensation 113.7 kilometers . . .. 7,983 
It is to be noted that in Solutions E, H, and G the density compensa- 
tion is assumed to be uniformly distributed to the depths named measured 
from the varying surface of the lithosphere. Of these solutions, G, having 
