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 earUer observations. I am 

 sure that 1 must often have swept, with a night-glass, over the 

 very spot where it stood in the mornings before sunrise. And 

 never 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 a colder region ; and that the first mo- 

 ment of this precipitation was precisely that I have pointed out 

 as the hmit 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^ccoi^w^ of a Level line measured from the 

 Bristol Channel to the English Channel, during the years 

 1837-8, hy Mr. Bunt, under the direction of a Coinmittee 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 level at Wick Rocks is 3.8 inches higher than at Por- 

 tishead. 



Prof. A. D. Bache, of iPhiladelphia, then communicated a " Note 

 on the effect of Deflected Currents of Air on thequaiitity 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 



