1866. | Annual Retrospect. 135 
pears to have been determined—namely, that the solar heat-rays pass 
through space without loss, and become effective only where wanted ; 
and, in proportion to the density of the atmosphere or the amount 
of water present in that through which they pass. If it be so, 
the proportion of heat received at Mercury, Venus, Jupiter, and 
Saturn may be the same as that received at the Harth, notwith- 
standing their different distances from the sun. 
Many subjects of much interest in this division of science en- 
gaged the attention of the Physical section of the British Asso- 
ciation ; amongst others, a self-recording anemometer was exhibited 
by Mr. 8. B. Howlett, and some of the records shown. ‘This in- 
genious instrument appeared to indicate that even the light breezes 
of summer have a tendency to move in circles, or to describe longer 
or shorter ovals, in their course. We learn that this apparatus is 
being manufactured at a moderate cost, and hence we hope that 
ere another year passes by, we may be in a position to report its 
capabilities and indications when used on a more extended scale. 
Although belonging to another division of Experimental Science, 
still, as having immediate relation to the above subjects, Professor 
Tyndall's researches on the Heat Spectrum, and especially on the 
phenomena to which he has given the name of Calorescence, must 
be regarded as of considerable importance. 
In the history of this interesting inquiry, the researches of 
Herschel (the elder), of Schenck, and especially of Melloni, must not 
be forgotten. We would especially direct attention to Melloni’s 
memoirs on ‘A New Nomenclature for the Science of Calorifie 
Radiations.* ‘The application of prismatic analysis to the objects 
in the heavens has been continued with much success. Mr. W. 
Huggins appears to have proved the gaseity of the nebule, and 
thus to have restored, to some extent, confidence in the “ nebulous 
fluid” of Sir W. Herschel, from which by subsidence and condensa- 
tion stars are supposed to be elaborated. Father Secchi, from a 
careful examination of the spectrum of Jupiter, shows that the- 
atmosphere of that planet has a peculiar and strong absorbing 
power, different from the atmosphere of the Earth. He thus ad- 
vances towards the proof required by Mr. Glaisher’s observations, 
* © Bibliotheque Universelle de Geneve,’ No. 70, for October, 1841. Translated 
in ‘Scientific Memoirs,’ vol. iii., part 12. 
