Chase.l ^^ [April 16, 



tween Sun's surface and } Mercury ; 9 at loci of theoretical planetary- 

 rupture ; 9 between |- Neptune and the region of the fixed stars. 



^. The 27th abscissa from Sun's surface, or the 19th from f , (^ry"^^"), 

 is L M -=- 7"o ; M being the elastic modulus of light at Sun's surface. (L = 

 36.36 ro; M = 474600 ?v) 



7j. The 28th abscissa from Sun's surface, (f//"^^""), is 46352440. Four re- 

 cent estimates of the distance of « Centauri range between 45340000 and 

 48479500. Searle* cites authorities ranging between 44252. 00 and 49169000. 

 Newcomb says.f "The mean of all the measures of tlie parallax of this 

 pair of stars hitherto made, gives 0",93 as their most probable parallax, 

 corresponding to a distance of 221000 astronomical units." This is equiva- 

 lent to 47463340 r^. 



It will be readily seen that the elements of the paraboloid, {\ r^, L, M), 

 are entirely independent of any observed or theoretical planetary distance. 

 No values can be assumed for those elements, within the limits of possible 

 uncertainly, which will weaken the evidence that the nebula-rupturing 

 position of the several planets, the time of solar rotation, and the inter- 

 stellar spaces, have been determined by the laws whicli govern luminous 

 undulation. 



VL Oosmical Determination of JouWs Equivalent. 



In estimating heat of dissociation, Pfaundler has shown:!^ that the mean 

 should be taken between the temperatures of incipient and of complete 

 dissociation. On this principle, in estimating tlie temperature of water- 

 crystallization we should have regard to all stages of the expansion in 

 molecular rearrangement, and take the mean (35°. 6 F. := 2°C) between 

 the temperatures of greatest density (39°«.2 F = 4°C) and of complete crys- 

 tallization (32° F = O^C). So long as water continues to condense, its 

 tendencies are centripetal and polar ; while it is expanding, they are cen- 

 trifugal and equatorial. The thermodynamic relations between heat and 

 work should be shown in the comparative motions and temperatures of 

 polar and equatorial waters, as surely, and with as abundant facilities for 

 accurate measurement, as in the experiments of the laboratory or in the 

 processes of the worksliop. 



Johnston's Physical Atlas gives 82°. 6 F (28°. IC) as the mean tempera- 

 ture of the oceanic warmth-equator. This indicates a polar-equatorial 

 difference of 82°.6 — 35°.6 F = 47 J, or 28°.l — 2^0 = 26.1 calories. 

 The difference in gravitating measure can be readily deduced from 

 the differences of motion. The velocity of equatorial rotation is 



1525.78 feet, which represents a fall of ( ifi^^:!?)" x 16, 044 ft. = 4.7 J. Hence 



we find J = 771.816 foot-pounds ; Calorie = 423.44 kilogrammetres. 



* Outlines of Astronomy, p. 396. 



t Popular Astronomy, p. 208, foot note. 



JPogg. Ann., 1867, 131, 6D3. 



