the "Crucial-Test" Argument. 491 



the specific gravity of column A exceeds that of the equatorial 

 by only -000009, a quantity which does not amount to 1 inch 

 in 1500 fathoms ! Sounding- No. II. of the Table, made at a 

 place a few degrees to the east of column B of the section^ gives 

 l-0.26.23_, which may be regarded as the mean specific gravity of 

 this column, and the more sr> as another sounding made in this 

 region gives identically the same mean value. The difference 

 between the equatorial column and the Atlantic column B in lat. 

 23° N. therefore amounts to only -000028, or 3 inches in 1500 

 fathoms. It must of course be observed that, as the specific 

 gravities in the Table are not taken at equal intervals, the mean 

 of the figures does not represent the mean specific gravity of a 

 column. The number of fathoms represented by each separate 

 value must be taken into account in determining the mean value 

 of the column. My former result, therefore, is not materially 

 affected, even after I have thus taken into account difference of 

 salinity, and computed the amount of expansion according to 

 Professor Hubbard's Table. The surface of the Atlantic in lat. 

 38°, to be in static equilibrium, must be 3 feet 3 inches above 

 that of the equator, and, in lat. 23°, 2 feet 3 inches above it. 



It is perfectly true that, according to the gravitation theory, 

 the ocean is never in a state of static equilibrium ; but it must be 

 observed that, as the surface-flow according to this theory is from 

 the equator polewards, it is the equatorial column that is kept 

 constantly below the level necessary to static equilibrium ; hence 

 were T to make allowance for want of static equilibrium I should 

 make the slope greater than 3 feet 3 inches. Dr. Carpenter's 

 objection that the force of my argument rests on the assumption 

 that the sea is in static equilibrium, is based on a misapprehen- 

 sion of the problem ; for in reality, by not making allowance for 

 want of equilibrium, I give his theory an advantage which it does 

 not deserve. Were the surface-flow from the North Atlantic to 

 the equator, there would then be some grounds for his objection ; 

 for by leaving out of account the want of equilibrium I should be 

 making the slope greater than it should be. 



I submit that the foregoing is a satisfactory proof that the 

 North Atlantic must be above the level of the equator ; and if 

 so, it shows the mechanical impossibility of a surface-flow pole- 

 wards in that ocean resulting from gravitation. 



