Mr. Daniell on a New Register-Pyrometer. 261 



1827—1830, at 10'' a.m. and lO'' p.m. is 9°-4 Reaumur, or 

 53° 15 Fahr. When we correct this result by +0*122, the 

 quantity by which the mean of lO*" and 10'^ differs from that 

 of the 24 hours, we obtain, Fahr. 



Corrected mean temp, of Sevastopol 53°'272 



Mean temp, calculated by formula T = 86°'3 

 sin. D — 3°!*, D the dist. from the Asiatic Pole 

 beina: = 4.1° 22' 53 -534. 



Difference between the formula and the observation + 0°*262 

 The coincidence is here very striking, the difference amount- 

 ing only to a quarter of a degree of Fahrenheit. D. B. j 



XLIX. Further Experiments isoith a ne'w Itegister-Pyrometer 

 for Measuring the Expansion of Solids. By J. Frederick 

 Daniell, Esq. F.R.S. Professor of Chemistry iuKing^s Col- 

 lege, London. 



[Concluded from page 204.] 



T NOW arranged the two bars in two registers ; and having 

 -* strongly heated the furnace and filled the air-chamber itself 

 with coke, I cleared out a space in which they could be placed, 

 without coming in contact with the fuel on each side of them. 

 Their two ends rested on pieces of fire-brick ; the wrought- 

 iron was placed lowest, and, the thickness of the register, in 

 advance of the cast-iron ; which was placed about two inches 

 higher. The apertures were now all closed, and the draught 

 increased to the utmost. At the expiration of a quarter of an 

 hour the register with the cast-iron was removed with a pair 

 of tongs; and the metal upon lifting it, immediately flowed 

 out at the two end holes. The register, with the wrought-iron 

 was then taken out. The bar of the latter was found perfect 

 without any signs of oxidation or fusion. 



The arc measured of the cast-iron was 9° 47' 



The arc of the wrought-iron .♦ 7 56 



I had some reason to think that the register, with the 

 wrought-iron bar, had not been exposed so fully to the heat 

 as that with the cast-iron : for, although placed slightly in ad- 

 vance of the latter towards the body of the furnace, it was not 

 raised so high from the floor of the flue, which probably liad 

 a cooling influence; and as the flame was drawn upwards, it 

 must have struck with greater force upon the higher register. 

 I therefore replaced the wrought-iron bar in the register, and 



* In this formula in Number 2. p. 136, place the comma that is after 

 the second D, before it. 



