606 PHILOSOl'HICAL TRANSACTIONS. [aNNO 1775. 



2d room, by plunging into water heated to 100°; and after having been wiped 

 dry, was carried home in a chair ; but the circulation did not subside for 2 hours, 

 after which he walked out in the open air, and scarcely felt the cold. 



Exper. 1. In the first room the highest thermometer varied from 132° to 130°; 

 the lowest stood at 119°. Dr. Fordyce having undressed in an adjoining cold 

 chamber, went into the heat of 119°; in 4. a minute the water poured down in 

 streams over his whole body, so as to keep that part of the floor where he stood 

 constantly wet. Having remained here 1 5 minutes, he went into the heat of 

 130° ; at this time the heat of his body was 100°, and his pulse beat 126 times 

 in a minute. While Dr. Fordyce stood in this situation, he had a Florence 

 flask brought in, filled with water heated to 100", and a dry cloth, with v;hich 

 he wiped the surface of the flask quite dry ; but it immediately became wet 

 again, and streams of water poured down its sides ; which continued till the heat 

 of the water within had risen to 122°, when Dr. Fordyce went out of the room, 

 after having remained 15 minutes in a heat of 130°; just before he left the 

 room his pulse made 1 39 beats in a minute, but the heat under his tongue, in 

 his hand, and of his urine, did not exceed 100°. Here Dr. Fordyce observes, 

 that as there was no evaporation, but constantly a condensation of vapour on 

 his body, no cold was generated but by the animal powers. At the conclusion 

 of this experiment. Dr. Fordyce went into a room where the thermometer stood 

 at -43°, dressed himself there, and immediately went out into the cold air, with- 

 out feeling the least inconvenience ; on which he remarks, that the transition 

 from very great heat to cold is not so hurtful as might be expected, because the 

 external circulation is so excited, as not to be readily overcome by the cold. Dr. 

 Fordyce has since had occasion, in making other experiments, to go frequently 

 into a much greater heat, where the air was dry, and to stay there a much 

 longer time, without being aflTected nearly so much ; for which he assigns 2 

 reasons ; that dry air does not communicate its heat like air saturated with mois- 

 ture ; and that the evaporation from the body, which takes place when the air 

 is dry, assists its living powers in producing cold. It must be immediately per- 

 ceived that, besides the principal object, these curious experiments throw great 

 light on many other important subjects of natural philosophy. 



January 23. The Hon. Captain Phipps, Mr. Banks, Dr. Solander, and Dr. 

 Blagden, attended Dr. Fordyce to the heated chamber, which had served for 

 many of his experiments with dry air. They went in without taking oft' any of 

 their clothes. It was an oblong-square room, 14 feet by 1 2 in length and width, 

 and 11 in height, heated by a round stove, or cockle, of cast iron, which 

 stood in the middle, with a tube for the smoke carried from it through one of 

 the side walls. When they first entered the room, about 2 o'clock in the after- 

 noon, the quicksilver in a thermometer, which had been suspended there, stood 



