1874.] Notices of Books. 247. 
ception of the quantitative force of gravitation due to its 
necessary inverse variation with the square of the distance 
vitiates completely all the reasoning based upon it. 
A further confusion is introduced by another paradox, which 
appears to be of Mr. Jordan’s own invention, viz., ‘the motive 
force termed evanescence.” We are told that it implies a motion 
of the evanescing particles, and gravitation tending to cause 
contraction necessitates a motion of the remaining particles; 
and since contraction is a necessary consequence of evanescence, 
having effect wherever evanescence occurs, it must act towards 
every point from which evanescence acts, and thus divide the 
universe into separate masses, and also that “‘ certain forces are 
in play, causing constant change of form and place; and to the 
combined action of these forces (to which no name has hitherto 
been given) I have applied the term evanescence.” 
In spite of these explanations and a good deal more of similar 
disquisition, we confess our inability to understand evanescence. 
When, however, Mr. Jordan fairly plunges into his proper 
subject, the Ocean, and deals with the phenomena of its currents 
apart from his paradoxical notions of “ inertia,” &c., he displays 
an amount of careful study and research that render his errors 
concerning fundamental physical laws the more vexatious. 
Some of his critical discussions of the theories of others are as 
remarkable for their clearness as his exposition of his own theories 
are for their obscurity. The following passage is an example.” 
“It seems to me that the manner in which gravitation 
would tend to restore disturbance of the normal level, such as 
those indicated by Dr. Carpenter, would naturally be by tidal 
movements, or easy, imperceptible movements of the whole 
mass of water intervening between the higher and lower levels, 
the former sinking and the latter rising simultaneously, just as 
when a trough half full of water is tilted on one side, the level 
of the water is maintained, not by the surface water streaming 
over the lower side, but, excepting the effects of friction against 
the sides and bottom of the trough, by an equable motion of the 
whole mass of water.” 
‘When a narrow channel lies between the higher and lower 
level, as in the case of the Mediterranean and Baltic, this 
movement would form a rush of water through the Strait, but not 
an upper rather than an under current. It so happens that, in 
both these cases, so elaborately considered by Dr. Carpenter, 
the higher level is also the lighter water; and, therefore, by 
Captain Maury’s simple theory, the specific gravity is restored, or 
an increase of the difference prevented by the heavier water 
running as an under current towards the lighter, and the lighter 
as an upper current towards the heavier. Suppose that instead 
of the lighter water being at the higher level, as in these two 
cases, the heavier were so, will any one contend that the level 
would be restored by a surface current from the higher to the 
