THE LAWS OF CONDUCTION OF HEAT IN BARS. 



81 



TABLE II. — Stationary Excesses of Temperature (prom all the Projections) 



adopted. 



Distance from Origin 

 at Crucible. 



Excess of Temperature (Centigrade) of Bar above Air. 



Case I. 

 1 1 inch Bar, naked. 



Case II. 

 1J inch Bar, covered. 



Case III. 

 1 inch Bar, naked. 



inch 

 1 

 2 

 3 

 4 

 5 

 6 



75 

 9 

 10-5 

 I. foot inch 

 3 

 6 

 9 

 II. feet 

 3 

 6 



III. „ 



6 



IV. „ 

 V. „ 



VI. „ 



VII. „ 



VIII. „ 



275-5 c. 

 242-9 c. 

 214-8 c. 

 1905 

 168-3* 

 1506* 

 134-7 

 114-1* 

 97-3 

 84-0* 

 72-0 

 53-6 

 40-8 

 31-0 

 24-2 

 18-9* 

 14-8 

 9-33 

 6- 15* 

 4-0 

 1-8 

 0-9 

 0-50 

 0-28f 



260-5 c. 

 221-7 c. 

 189-5 c. 

 162-9 

 140-0* 

 121-5 

 105-9 

 86-6 

 71-3 

 59-0 

 49-2 

 34-5 

 24-6' 

 17-7 

 13-0 

 9-45 

 70 

 3-8 

 2-1* 

 1-28 

 0-47 

 0-165+ 



282-2 c. 



243-2 c. 



2102 c. 



182-2 c. 



159 



137-5 :; - 



120-5* 

 99-8 

 82-8* 

 68-6 



57-1 

 40-9* 

 29-5 

 21-6 

 15-65* 

 11-5* 

 8-55* 

 4-95* 

 2-78* 

 1-56 

 0-55 

 0-13* 



The numbers marked c. are derived from calculation. See Art 68 below. 

 The numbers marked thus * belong to points in the curve not closely ad- 

 jacent to points of observation ; and, therefore, are less certain than the others. 

 •f* 0*32 by mean of 7 observations. +. Mean of 4 observations. 



Adjacent to the principal curve of Plate III. is a dotted curve, which exhibits the 

 remarkable change of character in the curve when the bar is coated with a highly 

 radiating surface of paper (Case II., Art. 48). 



62. Formula? of Interpolation for the Statical Curves. — It was not originally 

 my intention to have entered on the thorny enterprise of seeking equations 

 to satisfy the statical curves of temperature. My original plan (Art. 6 of former 

 paper) was to deal with Curves alone, or almost entirely. And when we do 

 not wish to exceed the limits of direct observation, it is perhaps the safest, 

 as well as by far the easiest plan. I wished, however, to throw all pos- 

 sible light on the problem, for the benefit of those who may hereafter extend 

 these observations. I also wished to obtain the greatest amount of informa- 

 tion from the data at my disposal; and by means of formulae, to extend the 

 results somewhat (though not far) beyond the limits of observation. It will 



VOL. XXIV. PART I. Z 



