of sea waters , in diffemit parts of the ocean, &c. 175 
In endeavouring to connect together the various state- 
ments contained in the above tables, the following inferences 
present themselves. 
The ocean in the southern hemisphere, would appear to 
contain more salt than in the northern hemisphere, in the 
proportion of 1029,19 to 1027,57 ; as may be seen by taking 
the mean specific gravity of the waters collected from the 
two hemispheres. But it must be observed, that a great pro- 
portion of the specimens from the northern hemisphere were 
taken farther from the equator than those procured from 
the other hemisphere, which may possibly account for the 
difference in question.* 
The mean specific gravity of specimens taken from various 
parts of the equator is 1027,77, and is therefore a little 
greater than that which prevails in the northern hemisphere, 
though sensibly less than that of the southern ocean. 
There is no notable difference between different east and 
west longitudes at the equator ; nor is there, in other lati- 
tudes, any material and constant difference between waters of 
the ocean in corresponding east or west longitudes in the 
same hemisphere. 
There is no satisfactory evidence of the sea, at great depths, 
being more strongly impregnated with salt than it is near 
the surface ; except under peculiar circumstances, which will 
* It may be observed also that Dr. Davy, in the experiments abovementioned 
(Philos. Trans. 1817), generally found the specific gravity of -sea water, both in the 
South Atlantic and in the Indian Ocean, lower than I have done ; for which I am at a 
loss to assign any reason, unless it be supposed that some of my specimens, from having 
been long kept, and perhaps not corked with sufficient care, may have undergone 
some degree of concentration. 
