98 



PRINCIPAL FORBES ON AN EXPERIMENTAL INQUIRY INTO 



be constructed. Dividing the length of the bar into sections, in the three experi- 

 mental cases so often referred to, the ordinates of the curve of statical cooling, or 



dv 



values of — j-, appropriate to every point of the bar, will be found as in the 

 following Table: — 



TABLE VIII. — Showing the Rate of Cooling proper to each Point of the Length 

 of the Bar (or Ordinates of the Statical Curve of Cooling) , containing also the 



dv 



VALUES OF — 



dx 



Distance from Origin 

 in Feet and Inches. 



Case I. 



Case II. 



Case III. 



dv 

 dl 



dv 

 dz 



dv 

 dt 



dv 

 dx 



dv 

 dl 



dv 



dz 



Ft. In. 



„ o 



„ 1 

 „ 2 

 „ 3 

 » 4 

 „ 5 

 „ 6 

 „ 7-5 

 „ 9 

 I. 

 6 

 II. 



III. 



IV. 

 VI. 



o 



4-71 



4-32 



3-97 



3-64 



332 



301 



2-70 



2-20 



1-80 



1-245 



0-620 



0-342 



0114 



0043 



0008 



O 



420 

 362 

 314 

 272 

 237 

 2068 

 1810 

 1488 

 1230 

 85-35 

 43-70 

 2447 

 815 

 334 

 0-57 



O 



830 



706 



605 



5-20 



4-41 



3-73 



314 



2-48 



1-98 



1-28 



0-58 



0-282 



0070 



0021 



O 



512 

 423 

 351 

 292 

 245 

 206-5 

 1752 

 1376 

 1090 

 699 

 35-2 

 163 

 4-47 

 1 36 



o 



6-75 



5-92 



519 



4-54 



400 



344 



293 



233 



1-85 



1185 



055 



0-258 



0070 



00185 



o 



512 



432 



366 



310 



264 



226 



1936 



1546 



1241 

 81-6 

 380 

 1964 

 5-52 

 169 



dv 



N.B. — The values of —-r are computed by the method explained in Art. 71. Only 



at some of the lower temperatures a mixed method of calculation and projection has been 

 used. 



09. It is evident that, if we can effect the quadrature of successive sections of 

 the statical curve of cooling, continued until it vanishes in the direction of the 

 cool end of the bar, we shall have got the " flux of heat" across the section of the 

 bar at which the quadrature commences. The measure of the heat expressed by 

 the area of the curve in question will have for unit the amount of heat required 

 to raise unit of volume (1 cubic foot) of iron by 1° Cent. The shaded curve, 

 in the lower part of Plate III., shows the Statical Curve of Cooling proper to 

 Case I. The ordinates of the curve are related to those of the curve of statical 



temperature immediately above it, by the relation of — y to v, shown in the 



secondary curve of cooling in the upper figure of Plate V. 



