a. ” 
MA ITIME OBSERVATIONS. 83 
periments mentioned in his defcription of the courfe of 
the gulph ftream, an account of which w as annexedto his 
maritime obfervations, and publifhed in the. Philofophi- 
cal Tranfactions Vol. Il. page 328, I then determined to 
repeat theie experiments in my future voyages. Accordingly 
on a paflage from Bofton to Virginia in OGober 178g, I 
kept a journal of the heat of the air and water at funrife, 
noon and funfet; I then noticed that the fea water out of 
foundings was about ten degrees warmer than that on the 
coait, and it very naturally occurred to me that the ther- 
mometer might become an ufeful nautical inftrument to 
indicate an-approach to the fhore. I thought it prudent, 
however, to keep this idea to myfelf till after I had made 
a courfe of fair and repeated experiments, which I ac- 
cordingly did during four paflages, 1ft, the one from Bof- 
ton to Virginia abovementioned, 2d from Virginia to 
England, 3d, from England to Hallifax, and 4th, from 
Hallitax to New-York. By confulting thefe journals and 
the obfervations made at the dates written, to»ether with 
thetracks of the fhip’s way marked on the chart annexed, 
it will not only appear that Doctor Franklin’s account’ of 
the warmth of the gulph ftream has been amply confirm- 
ed, but alfo that banks, coalts, iflands of ice, and rocks 
under water, may be difcovered when not vifible, and 
when the weather is too boifterous to found, with no other 
trouble than dipping the thermometer into the fea water.” 
It is well known to failors, that the water on the banks of 
Newfoundland is cold, but as they only try this, with 
the hand, their remarks are contradictory owing to the 
varicd temperature of the hand, and I never heard of any 
further application of what they think merely a matter of cu- 
riofity. Dod. Franklin’s obfervations had the knowledge of 
currents fortheir object, and this extenfionof his difcovery 
did not occur; butas I am indebted to his inftruGive con- 
verfation and example, for my inducement to purfue 
L 2 philofophical] 
