TABLE OF CONTEXTS. Vll 



ART. PAGE 



60. When a heated body is placed in an aeriform medium at a lower tem 

 perature, it loses at each instant a quantity of heat which may be 

 regarded in the first researches as proportional to the excess of the 

 temperature of the surface over the temperature of the medium . . 43 



61 64. The propositions enunciated in the two preceding articles are founded 

 on divers observations. The primary object of the theory is to discover 

 all the exact consequences of these propositions. We can then measure 

 the variations of the coefficients, by comparing the results of calculation 

 with very exact experiments ......... t&. 



SECTION IV. 

 OF THE UNIFORM AND LINEAR MOVEMENT OF HEAT. 



65. The permanent temperatures of an infinite solid included between two 

 parallel planes maintained at fixed temperatures, are expressed by the 

 equation (v - a) e = (b - a) z ; a and 6 are the temperatures of the two 

 extreme planes, e their distance, and v the temperature of the section, 

 whose distance from the lower plane is z . . . ..... 45 



66, 67. Notion and measure of the flow of heat ...... 48 



68, 69. Measure of the conducibility proper ....... 51 



70. Remarks on the case in which the direct action of the heat extends to 



a sensible distance ........... 53 



71. State of the same solid when the upper plane is exposed to the air . . 6. 



72. General conditions of the linear movement of heat ..... 55 



SECTION V. 



LAW OF THE PERMANENT TEMPERATURES IN A PRISM OF SMALL THICKNESS. 



7380. Equation of the linear movement of heat in the prism. Different 



consequences of this equation .... ..... 56 



SECTION VI. 



THE HEATING OF CLOSED SPACES. 



81 84. The final state of the solid boundary which encloses the space 

 heated by a surface 6, maintained at the temperature a, is expressed by 

 the following equation : 



m-n^(a-n) 



The value of P is ( ~ + + -f- ) , ?n is the temperature of the internal 

 s \fi K H J 



air, n the temperature of the external air, g, h, H measure respectively 

 the penetrability of the heated surface &amp;lt;r, that of the inner surface of the 

 boundary s, and that of the external&quot; surface s ; e is the thickness of the 

 boundary, and K its conducibility proper ....... 62 



85, 86. Remarkable consequences of the preceding equation 65 



87 91. Measure of the quantity of heat requisite to retain at a constant 

 temperature a body whose surface is protected from the external air by 



