REPORTS 
ON 
THE STATE OF SCIENCE. 
Report on the recent progress of discovery relative to Radiant 
Heat, supplementary to a former Report on the same sub- 
ject inserted in the \st volume of the Reports of the British 
Association for the Advancement of Science. By the Rev. 
BapeEn PowsE tt, M.A., F.R.S., F.R.Ast.S., F.G.S., Savilian 
Professor of Geometry in the University of Oxford. 
Havine been one of those whoat the first institution of the 
British Association were applied to, to prepare reports on the 
state and progress of the different branches of science, and ha- 
ving in consequence laid before the Association at the Oxford 
meeting in 1832 such a review of the subject of Radiant Heat, 
I have felt peculiar satisfaction in being again honoured by a 
request from the Council to furnish a second report supplement- 
ary to the former, embracing the progress of knowledge in that 
department from the period to which the first report extends, 
up to the present time. 
Such a supplementary account has been rendered peculiarly 
necessary, from the great number and high importance of the 
results which have been arrived at by several eminent experi- 
meuters in the interval which has elapsed: and though much 
is still required to be done before we attain complete and satis- 
factory grounds for an unexceptionable theory of radiant heat, 
yet the discoveries recently made have at least tended greatly 
to modify all our previous conceptions, and to enable us to refer 
large classes of the phenomena to something like a simple and 
common principle. 
In my former Report I divided the subject under various heads, 
derived from what appeared, in the existing state of our know- 
VOL, 1x. 1840. B 
