664 



Earth, and from various Bodies placed on, or near the surface of 

 the Earth." By James Ghiisher, Esq, Communicated hy G. B. 

 Airy, Esq., F.R.S., Astronomer Royal, &c. 



The author enters into a very detailed description of the construc- 

 tion of the thermometers he employed in these observations, and 

 the precautions he took to ensure their accuracy ; and gives tabular 

 records of an extensive series of observations, amounting to a num- 

 ber considerably above ten thousand, with thermometers placed on 

 nearly a hundred different substances, exposed to the open air, 'under 

 different circumstances, and in various states of the sky, at the Royal 

 Observatory at Greenwich. 



February 18, 1847. 



The MARQUIS OF NORTHAMPTON, President, in the Chair. 



Edward John Rudge, Esq., was elected a Fellow of the Society. 



" On the Diurnal Variation of the Magnetic Declination of St. 

 Helena." By Lieut.-Colonel Edward Sabine, R.A., For. Sec. R.S. 



It has long been knov/n that the diurnal variation of the magnetic 

 needle is in an opposite direction in the southern, to v/hat it is in 

 the northern hemisphere; and it v/as therefore proposed as a pro- 

 blem by Arago, Humboldt and others, to determine whether there 

 exists any intermediate line of stations on the earth where those 

 diurnal variations disappear. The results recorded in the present 

 paper are founded on observations made at St. Helena during the 

 five consecutive years, from IS^l to 1845 inclusive; and also on 

 similar observations made at Singapore, in the years 1841 and 1842; 

 and show that at these stations, which are intermediate between the 

 northern and southern magnetic hemispheres, the diurnal variations 

 still take place ; but those peculiar to each hemisphere prevail at 

 opposite seasons of the year, apparently in accordance with the 

 position of the sun with relation to the earth's equator. 



February 25, 1847. 



The MARQUIS OF NORTHAMPTON, President, in the Chair. 



The Earl of Hardwicke was elected a Fellow of the Society. 

 Rev. J. O. W. Haweis, M.A., was put to the ballot, but not 

 elected. 



" On certain Properties of Prime Numbers." By the Right 

 Hon. Sir Frederick Pollock, M.A., F.R.S., Lord Chief Baron of 

 the Exchequer, &c. 



