and the Mode of its Communication. 25 



is closed at both ends, and has a narrow cylindrical 

 neck, by which it is occasionally filled with hot water. 



This vessel, being covered with a garment made to 

 fit it, composed of any kind of cloth or stuff, or other 

 warm covering, is supported in a vertical position on a 

 wooden stand, which is placed on a table in a large 

 quiet room ; and one of the thermometers above de- 

 scribed being placed in the axis of the vessel, the time 

 employed in cooling the water, through the clothing 

 with which the instrument is covered, is observed and 

 noted down. 



Now, as the time of cooling through any given inter- 

 val of the scale of the thermometer (or from any given 

 degree above the temperature of the air of the room to 

 any other given lower degree, but still above the tem- 

 perature of the air of the room) will be longer or 

 shorter as the covering of the instrument is more or 

 less adapted for confining heat, it is evident that the 

 relative warmth of clothing of different kinds may 

 be very accurately determined by experiments of this 

 sort. 



I provided four instruments of this kind, all very 

 nearly of the same dimensions. Their cylindrical bodies 

 are each 4 inches in diameter and 4 inches long; and 

 their cylindrical necks are about T 8 ^ of an inch in diam- 

 eter, and 4 inches in length. This neck is placed in 

 the centre of the circular flat top, or upper end, of the 

 vertical cylindrical body; and opposite to it, in the 

 centre of the flat bottom of the body, there is a hollow 

 cylinder, -fa of an inch in diameter and 3 inches long, 

 projecting downwards, into which a vertical cylinder of 

 wood is fitted, on the top of which the instrument is 

 supported, in such a manner that the air has free access 



