PASSAGE OF HEAT THIlOUaH FLUIDS. 359 



The lower end of the tube of this funnel is surrounfled by a Apparatus for 

 projecting edge, or flanch, in the form of a hollow inverted fl^yj- 

 cone. The diameter of this conical projecting brim above, at 

 its base, is /o" <^^ an inch, and it is soldered below to the end 

 of the tube. 



When hot water is poured into the funnel, this liquid, de- 

 scending by the tube of the funnel, strikes against the inner 

 surface of the hollow inverted cone, which terminates the ver- 

 tical tube that belongs to the vessel, NO, and then rising up 

 through this last tube into that vessel, it runs oft" by its spout. 

 It was with a view to force this water to come into more inti- 

 mate contact with the hollow cone, that the projecting edge, in 

 form of an inverted cone, was added to the lower end of the 

 tube of the funnel. 



The object chielly in view in the arrangement of this appa- 

 ratus, was to give to the conical point which terminates the 

 vertical tube of the vessel, NO, an elevated temperature, 

 which should remain constant during some time, for the pur- 

 pose of observing if the heat, which must necessarily be com- 

 municated by this metallic point to the small quantity of water 

 with which it is in contact, and which is confined in the lower 

 .part of the wooden tube, M, would descend, or not, to the 

 thermometer which was placed in the wooden cup. 



There was still one source of error and incertitude 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, KL, might be transported to tlie 

 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 manner. 



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 communiCa^ 

 ted the excess ofheat they had received from the wooden tube. 



Tiiis 



