of sea waters, in different parts of the ocean, &c. 177 
I have before mentioned, by means of which he flattered him- 
self that water could be brought up from any desired depth ; 
and it was upon the same occasion that I contrived the appa- 
ratus above described, in hopes that it would enable me to 
obtain water from the bottom of the Straits. My friend, Dr. 
Macmichael, one of the travelling Fellows of the University 
of Oxford, and Member of this Society, undertook to make 
the attempt. He succeeded in procuring water in the Straits, 
from the depth of two hundred and fifty fathoms, with Mr. 
Tennant's machine ; but all attempts to obtain water from 
the bottom proved fruitless, from the impossibility of reaching 
it on account of the very great depth of the sea in that spot.* 
The specimens of water, however, procured by Mr.TENNANT’s 
machine, were sent home, and were soon afterwards examined,’ 
in the presence of Dr. Macmichael, by Mr. Tennant, who 
could not detect any difference in their specific gravity ; and 
when I lately re-examined the same specimens, which had been 
preserved, it even appeared (probably from some accidental 
circumstance ) that the specimen from the surface was a little 
heavier than the other. This point therefore remains to be 
decided by farther investigation. 
With regard to the waters of the Atlantic, although no 
pains have been spared by the able and zealous officers em- 
ployed in the late voyages towards the Pole, to procure speci- 
mens of water, both from the surface and from great depths, 
with a view to compare their densities, and though I have 
* This attempt was made in Sept. 1811, in the Bay of Gibraltar, between Cape 
Europa and Cabrita. See Table III. 
A a 
MDCCCXIX. 
