Royal Society. 559 



rence of fossil wood and coal, and what is still more extraordinary, 

 these are imbedded in the igneous rocks. The wood, which is for 

 the most part highly silicified, is found enclosed in the basalt ; 

 whilst the coal crops out in ravines, in close contact with the over- 

 lying porphyritic and amygdaloidal greenstone. 



A few outline sketches of the rocks and scenery, in various parts 

 of the island, accompany this paper. 



A paper was also in part read, entitled, " On the proportion of 

 the prevailing Winds, the mean Temperature, and depth of Rain in 

 the climate of London, computed through a cycle of eighteen years, 

 or periods of the Moon's Declination." By Luke Howard, Esq., 

 F.R.S. 



April 29. — The reading of Mr. Howard's paper was resumed and 

 concluded. , 



In this paper the author investigates the periodical variations of 

 the winds, rain and temperature, corresponding to the conditions of 

 the moon's declination, in a manner similar to that he has already 

 followed in the case of the barometrical variations, on a period of 

 years extending from 1815 to 1832 inclusive. In each case he gives 

 tables of the average quantities for each week, at the middle of which 

 the moon is in the equator, or else has either attained its maximum 

 north or south declination. He thus finds that a north-east wind is 

 most promoted by the constant solar influence which causes it, when 

 the moon is about the equator, going from north to south ; that a 

 south-east wind, in like manner, prevails most when the moon is 

 proceeding to acquire a southern declination ; that winds from the 

 south and west blow more when the moon is in her mean degrees 

 of declination, going either way, than with a full north or south 

 declination ; and that a north-west wind, the common summer and 

 fair weather wind of the climate, affects, in like manner, the mean 

 declination, in either direction, in preference to the north or south, 

 and most when the moon is coming north. 



He finds the average annual depth of rain, falling in the neigh- 

 bourhood of London, is 25'17 inches. 



From his observations on the temperature, he deduces the follow- 

 ing conclusions: — 1. That the pressure of an atmospheric tide, 

 which attends the approach of the moon to these latitudes, raises 

 the mean temperature 0'3o of a degree. 2. That the rarefaction 

 under the moon in north declination lowers the temperature 0'13 

 of a degree. 3. That the northerly swell following the moon 

 as she recedes to the south further cools the air 0"18 of a degree. 

 4. That this cold continues while the moon is away south, reducing 

 the mean temperature yet lower by 0"04 of a degree*. 



The following papers were then read : — 



I. "A new Method of solving Numerical Equations." By Mr. 

 Thomas Weddle, of Stamfordham. Communicated by S. H. Christie, 

 Esq., M.A., Sec. R.S. 



The object of this pajier is to develope a new and remarkably 



[* On the subject of this paper see ante, p. 552 and p. 555.] 



