File:Transactions of the American Philosophical Society (1771) (14581566217).jpg

Identifier: transactionsofamns03amer (find matches)
Title: Transactions of the American Philosophical Society
Year: 1771 (1770s)
Authors: American Philosophical Society
Subjects: Science Social sciences
Publisher: Philadelphia : The Society
Contributing Library: University of Pittsburgh Library System
Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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e water, is warmerthan that over thofe which admit deep water between themand the coaft; but ftill it is colder than the adjacent fea. 5. The water within capes and rivers does not followthe above rules; it being lefs agitated, and more expofedto the heat of the fun, and to receive the heat from the cir-cumjacent land, muft be colder or warmer than that infoundings without, according to the feafons, and tempe-rature of the atmofphere. 6. The paflage, therefore, from deep to fhoal water maybe difcovered by a regular ufe of the thermometer, beforea navigator can fee the land; but as the temperature isrelative, no particular degree can be afcertained as a rule,and the judgement can only be guided by the difference.Thus in Auguft I found the water off Cape Cod to be 58^*by Fahrenheit, and at fea it was 69-; inOdober the wa-ter off Cape Cod was 48, and at fea it was 59. Thisdifference was equally a guide in both cafes, though theheat was different at different feafons. I t/T^ic.Jjy, iiJUSi
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MARITIME OBSERVATIONS. 85 I do not prefume to fay what is the caufe of this differ-ence of heat between the lea and bank water, but if a na-vigator were to obferve it when near an Ifland of ice, hewould very naturally fay that the ice conduced the heatfrom the circumjacent water, and left it colder than thatat a diftance. And as it is well known that ftones andfand are great conductors of heat, it feems probable thatbanks alfo conduct the heat from the adjacent water, thoughnot fo rapidly as the ice. The heat of the water may in-deed be fuppofed to feek its equilibrium, but as long asthe Illands of ice and banks continue to conduft, theremuft be fome diiference, and this it is, which, by attenti-on, maybe made a faithful lentinel to give an alarm whendanger is near. I have thought it my duty to prefent my journals as they■were written at fea, to avoid the luipicion of having addedany thing from the fuggeftions of the imagination. Whilethis will be received as a circumftance favourab

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