216 Royal Society. 



emitted with increased rapidity. He also then first perceived in the 

 centre of the cloud, a dull, red, obscure nucleus, or fire-ball, appa- 

 rently about half the diameter of the moon, having a tail five or six 

 times that length, from which the flashes mentioned were sent forth, 

 of surpassing brilliancy, as the meteor clearly descended with great 

 velocity through the air, accompanied by a detonating, hurtling, 

 hissing sound, impossible to describe, yet resembling that which 

 precedes the shock of an earthquake. At three minutes past five 

 o'clock A.M., the meteor having apparently spanned the Channel 

 from S.E. to N.W., upon approaching the land — evidently throw- 

 ing oflf portions of its substance as it passed through the atmo- 

 sphere — the nucleus suddenly exploded with a report similar to a 

 very heavy clap of thunder, giving out an intensely brilliant light, 

 which rendered the minutest objects distinctly visible, although it 

 rained violently and the sky was obscured by dark and threatening 

 clouds. The dense body of the meteorite seemed to fall in the 

 water about half a mile from the land, as indicated by a great vo- 

 lume of spray, which rose foaming in the distance. 



Feb. 3. — The reading of Mr. Airy's paper, entitled *' On the 

 Eclipses of Agathocles, Thales and Xerxes," commenced at a former 

 meeting, was resumed and concluded. 



The author, after remarking that the calculations of distant eclipses 

 made in the last century possess little value, proceeds to give the 

 successive steps of improvement in the lunar theory as applicable 

 to the computation of eclipses, and especially in the motion of the 

 moon's node. The first great improvement was the introduction by 

 Laplace of terras expressing a progressive change in the mean secu- 

 lar motions. With Biirg's tables, in which these changes were in- 

 troduced, or with the same elements, Mr. Francis Baily and Mr. 

 Ottmanns computed many eclipses in the search for that usually 

 called the eclipse of Thales ; and both these astronomers fixed upon 

 the eclipse of b.c. 610, September 30, as the only one which could 

 be reconciled with the account of Herodotus. Mr. Baily however 

 subjoined a computation of the eclipse of Agathocles from the same 

 elements, and found that this could not by any means be reconciled 

 with the historical account ; he inferred from this that some serious 

 change in the theory is necessary, and that when it was introduced 

 the eclipse of b.c. 610 might not be found to agree with history; 

 but he thought it certain that no other eclipse could be adopted. 

 The various values of the motion of the node adopted by diflferent 

 writers from different observations (principally total or annular 

 eclipses) are then collected. Allusion is then made to the peculiar 

 value of the eclipse of Stiklastad (brought to notice by Professor 

 Hansteen), and which will be increased when the calculations shall 

 have been made on unexceptional elements. The author then ad- 

 verts to the great Reduction of the Greenwich Observations from 

 1750 to 1830, to Hansen's new inequalities, and to the numerical 

 amounts of corrections of the principal elements. Then are given 

 the coeflicients of the change in secular value of mean motion of the 

 mean of the moon's perigee, and of the moon's node, as found by 



