654 Miscellaneous. [Dec. 
1827, vol. I. p.19.) Assume 100° of Farenheit, for the measure of the heat ex- 
perienced on the surface of the earth, by the direct influence of the sun’s rays. 
It is stated in the work above quoted, that silver melts at 22 degrees of Wrpe- 
woop, and as Tam not at present exactly aware, at what degree of heat iron 
becomes red hot, I will assume that of silver, just going into a state of fusion, 
instead of it*. 
Silver melts at 22° of WEpGwoop, and 22 multiplied by 130 plus 1077, equal 
3,937° of Farenheit*, therefore, the degrees of heat of the Comet, 2,755,500° 
divided by 3,937°, or heat of melting silver, will make the heat of the former, 700 
times greater than that of silver going into a state of fusion. 
(MAcLAURIN, without investigating the truth of the remark, says, the Comet con- 
ceived a heat, 2,000 times greater than that of iron almost going into fusion. This 
must be a mistake, for I find that iron fuses at 1589 WepGwoop, = 21,617° Faren- 
heit, so that, using this as a divisor, instead of 3,937°, we obtain only 1274 for the 
number of times excess of the Comet’s heat, over that of iron in a state of 
fusion). 
For gold under the same circumstances, 32° W. = 5,237° F., at which it melts - 
therefore 2,755,500° —- 5,237 = 526 times excess of the Comet’s heat over that 
of gold in a state of fusion. 
Tin melts at 442° F. (Fyre, vol. II. p. 35,) therefore 2,755,500 — 442 — 6,234 
times excess of do. over tin. (But at page 21, vol. I. Fyre says tin melts at 644 
F., therefore 2,755.500 —- 644 = 4,278 times do. do). 
Copper melts at 30° WepGwoop = 4,977°F., therefore 2,755,500 — 4,977 = 554 
times for the excess over copper, in a Similar state. 
Lead at 612° F.; therefore 2,755,500 —- 612 = 4,502 times of same over lead 
in fusion. 
I believe Sir Issac NewrTon’s mode of measuring the quantity of caloric, in 
heated bodies, was, by their rate or time of cooling, to a degree equal to that of 
the surrounding medium. 
It does not, however, so far as I can see, follow, that the interior, to the very 
centre of the comet, becomes heated by the sun to so great a degree, as is here 
indicated, and which affection applies to the surface particularly, for, the time that 
the Comet is exposed to the sun’s rays, its rate of motion being increased in pro- 
portion to its proximity to the sun, (so as always to describe equal areas in equal 
times,) would probably be of insufficient duration, for so large a body to conceive, 
to its centre, this immense degree of heat ; for, the comet has, no doubt, its sea- 
sons, and days and nights, as well as the earth, and much free space, almost void 
of the sun’s heat, or even his light, in which to lose its caloric. 
Since writing the above, I see by Mr. JamEs PRrinsEp’s experiments in the Asia- 
tic Journal, vol. ii. page 140), that iron heated “ uniformly to a glowing red,’”’ 
measured 1609° of temperature, Fahrenheit ; if this be used as a divisor, instead 
of the former denominator, for the melting silver, we shall obtain as follows: 
2,755,500 —- 1609 = 1712.554 times excess of the Comet’s heat over that of red 
hot iron. 
It is evident, that this amount must fluctuate, in exact proportion to the number 
of degrees, assumed for the measure of the sun’s heat, as felt u is o 
which I have taken at 100°; but it appears that the dune heat ‘Mannie oe 
Amonton’s thermometer, on one occasion, to the height of boiling water, or 212° 
Fahrenheit, (see Hurron’s Math. Dict. of 1815, p, 640). This would increase the 
* Vide Ferguson’s Astronomy, of 1790, p. 88. 
