574 , PHILOSOPHICAL TRANSACTIONS. [aNNO J701. 



136 . .44-. . Degree of heat with which ignited bodies glow by night, but not 

 at all in the twilight, and with this degree of heat both a 

 mixture of two parts of reguJus martis and one part of bis- 

 muth, as also a mixture of five parts of the said regulus and 

 one part of tin, by cooling hardens ; the regulus by itself 

 hardens with the heal of 146 parts. 

 161 .. 44-. . Degree of heat, by which ignited bodies manifestly glow in the 

 twilight immediately preceding the rising of the sun, or after 

 his setting, but not at all in a clear day, or but very faintly. 

 192 . . 5 . . Degree of heat of live coals in a small kitchen fire, made up of 

 bituminous pit- coals, and that burn without using bellows ; as 

 also, the heat of iron made as hot as it can be in such a fire ; 

 the degree of heat of a small kitchen fire made of figgots is 

 somewhat greater, viz. 200 or 210 parts, and that of a large 

 fire is still greater, especially if blown with bellows. 

 In the first column of this table are the degrees of heat in arithmetical pro- 

 portion, beginning with that which water has when it begins to freeze, being 

 as it were the lowest degree of heat, or the common boundary between heat 

 .and cold ; and supposing that the external heat of the human body is 12 parts. 

 In the second column are set down the degrees of heat in geometrical propor- 

 tion, so that the second degree is double the first, the third double the second, 

 and the fourth double the third ; and making the first degree the external heat 

 of the human body in its natural state. It appears by this table, that the heat 

 of boiling water is almost 3 times that of the human body, of melted tin 6 

 times, of melted lead 8 times, of melted regulus 12 times, and the heat of an 

 ordinary kitchen fire is 16 or 17 times greater than that of the human body. 



This table was constructed by means of the thermometer and red-hot iron. 

 By the thermometer were found all the degrees of heat, down to that which 

 melted tin ; and by the hot iron were discovered all the other degrees ; for the 

 heat which hot iron, in a determinate time, communicates to cold bodies near 

 it, that is, the heat which the iron loses in a certain time, is as the whole heat 

 of the iron ; and therefore, if equal times of cooling be taken, the degrees of 

 heat will be in geometrical proportion, and therefore easily found by the tables 

 of logarithms. First it was found by the thermometer with linseed oil, that if, 

 when it was placed in melted snow, the oil possessed the space of 10000 parts ; 

 then the same oil rarefied with the heat of the first degree, or that of a human 

 body, possessed the space of 10256 parts, with the heat of water just begin- 

 ning to boil, the space of IO705 ; with that of water strongly boiling, the space 

 of 10725 parts; with that of melted tin, beginning to cool, and to be of the 

 consistence of an amalgama, the space of 11516; and when it is quite hardened 



