1833.1 Miscellaneous. 655 



above amount (by 2. 12 times) to 3,630 times, but taking the general average heat 

 of the air, in the shade, in hot countries, at 70° only, the amount would be7-10tli3 

 of the above, =1200 times nearly; while for England, assuming 50° as a mean, 

 we have one half of the 1712^856 times excess of heat of the comet of 1680, over 

 that of iron raised to a glowing red : this is tolerably near the 900 times mentioned 

 by tha Burmese prince ; but the medium heat of air, out of doors in the shade in 

 England, is about 51. 4°, so that, multiplying 1,712. 554 above mentioned, by 

 51,4 = 514 we get 880^ for the excess of heat, differing only by 19| from the 

 answer sought : but we get it nearer, by using the lOOdth. part of the mean heat 

 of the thermometer, out of doors, =z 51.4 and of that within doors, 52.9 mean = 

 52-15 instead of the last mentioned ,514dth., for we have 52.15 for the multiplier 

 of 1,712,554, and the product is 893 times, instead of 900 as desired, and lastly, it 

 becomes still nearer, viz. 905.9 times, by using the mean heat within doors or 52°,9 

 as above. This will, I trust, be considered sufficiently near and satisfactory. (N.B. 

 It is equal to the quotient of (95.000000), 2 X (572,300) 2 X by x \%%)- 



Afer the above was written, I found in the 1st volume of the Gleanings of 

 Science, page 96, that Mr. Prinsep has noticed the little reliance which is to be 

 placed on Wedgwood's Pyrometer, the degrees of which I have used in the former 

 calculations : this will not, however, affect the answer last given, viz. 905.9 where 

 I have quoted that gentleman's own experiment, so that the statement is left 

 nearly as I had at first written it ; but as the measure of temperature, of some of 

 the metals there shewn, differs considerably from the corresponding ones here 

 noted, it is right to state, that in that work the metals are represented to melt, 

 at the undermentioned degrees of heat : 



Silver at 



"47770 p or it s equivalent of Wedgwood. 



2233° F do. Daniel. 



1830° F do. Prinsep. 



1822.7 F do. 



For melting Sil- 

 ver, 



>Morveau. 

 Gold at 2822,6 F do. J 



The degree of heat of the comet above fusing silver, &c. will therefore be as 



follows, taking 100° for our temperature : 



"2,755,500 + 4,777 = 576 times using Wedg-"| measure . 



wood's i ' , 



2,755,500 -f- 2,233 = 1,234 .. do. Daniel's >■ ine sot 



2,755,500 ~ 1,380 = 1,505 .. do. Prinsep's | , P ~,~ 



„ ~ ,, f 2,755,500 — 1,822.7 = 1,611 do. \ ., . I ralure - 



For Gold. ^ 2 ; 755 ; 500 4. 2 ' j517i6 _ { >m d0> JMorveau sJ 



Correction. 



Instead of 2,755,500 as a numerator, on the assumption of 100° being the heat 

 on the earth, take the medium heat, as before, 52°.15, and the quotient of 

 95,000,000' 2 -f- 572, 300 2 =or 1,436.990, and divide it by the degrees of the metal, 

 thus ; 



Than silver fusing, the comet is 308 times hotter, by using Wedgwood's degrees 



4,777, 



, - Do. 1.436,990-^2,233 = 643$ times by Daniel's Do. 



Do. 1,436,990+1,830 =785° Prinsep's Do, 



Do ' hfiMEti'HK = ?S£ 1 Morveau's Do. 



Gold l,436,990-r2,517.6 =570° 



