342 Z>. blagden on the Heat of 
tucket fhoals, a distance of more than 1000 miles from the 
gulf of Florida ! According to the calculation I have be- 
fore adopted of a lofs of two degrees of heat for every 3 0 of 
latitude, the temperature of the Gulf-ftream here would be 
nearly 73 0 ; the difference of which from 59 0 , the heat that I 
obferved in the fea-' water both before and after the gale, might 
eafiiy be perceived by the mafter of the veflel. This was in 
the winter feafon, at the end of December. 
An opinion prevails among feamen, that there is fomething 
peculiar in the weather about the Gulf-ftream. As far as I 
could judge, the heat of the air was confiderablv increafed by 
it, as might be expedted ; but whether to a degree or extent 
fufficieilt for producing any material changes in the atmofphere 
muft be determined by future obfervations. 
Perhaps other currents may be found which, iffuing from 
places warmer or colder than the furrounding fea, differ from 
it in their temperature fo much as to be difcovered by the ther- 
mometer. Should there be many fuch, this inftrument will 
come to be ranked among the moft valuable at fea ; as the diffi- 
culty of ascertaining currents is well known to be one of the 
greateft defedts in the prefent art of navigation. 
In the mean time, I hope the obfervations which have been 
here related are fufficient to prove, that in crofting the Gulf- 
ftream very effential advantages may be derived from the life 
of the thermometer : for if the mafter of a fhip, bound to any 
of the fouthern provinces of North America, will be careful 
to try the heat of the fea frequently, he muft difcover very 
accurately his entrance into the Gulf-ftream, by the fudden in- 
creafe of the heat ; and a continuance of the fame experiments 
will fhew him, with equal exadlnefs, how long he remains in 
it. Hence he will always be able to make a proper allowance 
