2 Be 
ae 
British Association for the Advancement of Science. 287 
it from a star. And, in fact, it was this very thing which caused 
Maclear and myself to miss procuring earlier observations. Iam 
sure that I must often have swept, with a night-glass, over the 
very spot where it stood in the mornings before. sunrise. And ~ 
hever was astonishment greater than mine, at seeing it riding 
high in the sky, broadly visible to the naked eye, when pointed 
out to me by Mr. Maclear, who saw it with no less amazement 
on the 24th.. The next remarkable feature, is the enormously 
rapid ‘rate of dilatation of the disc, and the absorption into it of 
all trace of the surrounding nebula. Another, is the interior co- 
metic nucleus. All these phenomena, while they contradict 
every other hypothesis that has ever been advanced, so far as I 
can see, are quite in accordance with a theory on the subject, 
which I suggested on the occasion of some observations on Biela’s 
comet,—a-theory which sets out from the analogy of the precipi- 
tation of mists and dews from a state of transparent vapor on the 
abstraction of. heat. It appears to me, that the nucleus and 
grosser parts of the comet, must’ have been entirely evaporated 
during its perihelion, and re-precipitated during its recess from 
the sun, as it came into acolder region; and that the first mo- 
ment of this precipitation was precisely that I have pointed out 
as the limit of the existence of the disc,—viz. on the 21st of Jan- 
uary, 1836, at 2 p. m., or perhaps an hour or two later. 
Rev. W. Whewell’s Account of a Level line measured from the 
Bristol Channel to the English Channel, during the years 
1837-8, by Mr: Bunt, under the direction of a Committee of the 
British Association, was read, the result of which is, that in July, 
1838, the sea level at Portishead, (near Bristol,) was found to be 
ten inches higher than that at_Axmouth ; according to which, 
the mean . ake at Wick Rocks is 3. 8 sipelin ies than at Bor. 
tishead. — 
Prof. A. D. Bache, of Philadelphia, ten cprritnnndented « « Note 
on the effect of Deflected Currents of Air on the quantity of Rain 
collected by a Rain-gauge,” the more remarkable phenomena no- 
ticed in it being represented by diagrams. Prof. Phillips’s first 
Report on the quantity of rain collected at different heights, in- 
duced Prof. B. to begin a series of observations near the end of 
1833. Philadelphia, from the extent of the plain on which it 
stands, was thought a good locality for this purpose. At first, 
_ gauges were placed at three different heights. One station was 
