4U ON- THE LOSS OF HEAT 



the bulb ; henee, motion in the fluid commences, and in pro- 

 portion to its heat will be its fluidity, and consequently, the 

 velocity with which the change will be made, and as the strata 

 lessen in volume as they approach the centre of the bulb, their 

 heat must either be transmitted through the exterior interven- 

 ing strata, or be subject to the necessary delay in coming in 

 contact with the bulb, in consequence of the decreasing velocity 

 with which the changes are made ; and, in either case, the cool- 

 ing process will be retarded. If we suppose the fluid, under 

 the circumstances described, incapable of locomotion, it will 

 not be denied that the interior strata will require more time 

 to impart the same heat than the exterior, consequently, pro- 

 portional to the cooling of the body must be the increased time 

 required to deprive it of any given number of degrees. 



Experiments upon this subject would be much more satis- 

 factory, and would probably give different results from those 

 hitherto obtained at high temperatures, by using an apparatus 

 which should admit of maintaining the heat at fixed points 

 upon the scale of the thermometer; in which case motion in 

 the fluid would be immaterial, and an equally heated surface 

 would always be exposed to the refrigerating medium. 



Experiments to determine the comparative loss of Heat sustained 

 by different constructions of apparatus ordinarily used for 

 the combustion of Fuel. 



The comparative loss of heat which arises from the different 

 manner in which fuel is consumed, is a subject intimately con- 

 nected with the question of economy in its use, but it is a distinct 

 subject of inquiry from the former investigation, which was to 

 determine the comparative heat disengaged in the combustion 

 of the various kinds of fuel. It is presumed the remarks 

 which have already been made, in anticipation, on this point, 

 in detailing the first course of experiments, (at page 23,) will 

 be considered conclusive- 



