INTRODUCTION. 39 



titude 13° and 14% when, 10^ fouth of them, nearly 

 under the Hne, all the people are white, as w^e had 

 an opportunity of feeing daily in the Galla, whom 

 we have defcribed. Cold and heat are terms merely 

 relative, not determined by the latitude, but by the 

 elevation, of the place. When, therefore, we Iliy 

 hot, fome other explanation is neccifary concerning the 

 place where we are, in order to give an adequate Idea 

 of the fenfation of that heat upon the body, and the ef- 

 feds of it upon the lungs. The degree of the ther- 

 mometer conveys this very imperfectly : 90 is excef- 

 fively hot at Loheia in Arabia Felix ; and yet the lati- 

 tude of Loheia is but 15% whereas 90 at Sennaar 

 is, as to fenfe, only warm, although Sennaar, as v/e 

 have faid, is in latitude 13°. At Sennaar then I call it 

 cold, when one, fully clothed and at reft, feels himfelf 

 in want of fire ; I call it cool, when one, fully clothed 

 and at reft, feels he could bear more covering all over, 

 or in part, more than he has then on ; I call it tempe- 

 rate, when a man, fo clothed and at reft, feels no fuch 

 want, and can take moderate exercife, fuch as walking 

 about a room without fweating; I call it warm, when a 

 man, fo clothed, does not fweat when at reft, but upon 

 moderate motion fweats, and again cools ; 1 call it 

 hot, when a man fweats when at reft, and exceilively 

 on moderate motion ; I call it very hot, when a man, 

 with thin or little clothing, fweats much though 

 at reft ; I call it exceinve hot, when a man, in his 

 fliirt at reft, fweats exceilively, when all motion is 

 painful, and the knees feel feeble as after a fever ; 

 I call it excefTive hot, when the ftrength fails, a cli- 



C 4 polition 



