282 Inquiries concerning the Mode of the 



The object chiefly in view in the arrangement of this 

 apparatus was to give to the conical point which termi- 

 nates the vertical tube of the vessel N O, an elevated 

 temperature, which should remain constant during some 

 time, for the purpose of observing if the heat, which 

 must necessarily be communicated by this metallic point 

 to the small quantity of water with which it is in con- 

 tact, and which is confined in the lower part of the 

 wooden tube M, would descend, or not, to the ther- 

 mometer which was placed in the wooden cup. 



There was still one source of error and uncertainty 

 against which it was necessary to guard. The heat 

 communicated through the sides of the wooden tube to 

 the water contained in the great cylindrical vessel K L 

 might be transported to the sides of that vessel, and, 

 being then communicated from above downwards 

 through these sides, might heat successively the lower 

 strata of the liquid, and at last that stratum in which the 

 thermometer was. 



It was to prevent this that the annular vessel H I was 

 used, and it performed its office in the following man- 

 ner: The particles of water contained in the great vessel 

 K L, which, being in contact with the exterior surface of 

 the wooden tube, were heated by that tube, could not fail 

 to rise to the surface, and there they 'necessarily came 

 into contact with the interior sides of the annular vessel, 

 to which they communicated the excess of heat they had 

 received from the wooden tube. 



This heat, passing readily through the thin metallic 

 sides of that vessel, was given off as fast as it was re- 

 ceived to the particles of cold water contained in the 

 vessel which were in contact with its sides, and these 

 particles, rising to the surface of the water con- 



