the Water in the Gulf f ream . 34 j 
for the number of miles that the (hip is fet to the northward, 
bv multiplying the time into the velocity of the current. 
Though this velocity is hitherto very imperfectly known, for 
want of fome method of determining how long the current 
acted upon the (hips, yet all uncertainty arifing from thence 
mud foon ceafe, as a few experiments upon the heat of the 
dream, compared with the fhip r s run checked by obfervatioris 
of the latitude, will afcertain its motion with diffident precri- 
(ion. From differences in the* wind, and perhaps other cir- 
cumdances, it is probable, that there may be fome variations 
in the velocity of the current; and it will be curious to ob- 
ferve, whether thefe variations may not frequently be pointed 
out by a difference in its temperature ; as the quicker the cur- 
rent moves, the lefs heat is likely to be lod, and confequently 
the hotter will the water be. In this obfervation, however, the 
feafon of the year mud always be confidered ; partly, becaufe 
it may, perhaps, in fome degree affeCt the original temperature 
of the water in the gulf of Mexico ; but principally, becaufe 
the aCtual heat of the dream mud be greater or lefs in propor- 
tion as the traCt of the fea through which it has flown was 
warmer or colder. In winter, I ffiould fuppofe, that the heat 
of the dream itfelf would be rather lefs than in dimmer ; but 
thrlt the difference between it and the furrounding fea would be 
much greater; and I can conceive that, in the middle of dim- 
mer, though the dream had lod very little of its original heat, 
yet the fea might, in fome parts, acquire fo nearly the fame 
temperature, as to render it fcarcel'y poflible to didinguiffi by 
the thermometer when a fhip entered into the current; 
Befides the convenience' of correcting a (hip’s courfe, by 
knowing how to make a proper allowance for the didance (he is 
fet to the. northward by the current, a method cf determining 
Z z 2 with 
