333 



of determining the longitude of any other point in that circle, from 

 its latitude. 



The third paper was entitled, " Hygrometrical Observations made 

 on board His Majesty's surveying vessel iEtna." Communicated 

 by Captain Beaufort, R.N., F.R.S. 



These observations extend from the 27th of March to the 6th of 

 July, 1834, and were made daily at 8 o'clock a.m., at noon, and at 

 4 o'clock p.m. They comprise the height of the barometer, the dew- 

 point, degrees of dryness on the thermometrical, and of moisture on 

 the hygrometrical scales, the elasticity of the vapour, and the number 

 of grains of vapour in a cubic foot j with occasional remarks. A se- 

 cond series is also given, exhibiting the progress of solar radiation. 



The fourth was a " Meteorological Register, from the 1st of Janu- 

 ary to the 1st of November, 1834," by Mr. Edward Barnett. Com- 

 municated by Capt. Beaufort, R.N , F.R.S. 



These observations, made during a voyage across the Atlantic, 

 relate chiefly to the temperatures of the air, and of the surface of 

 the sea. 



The fifth was a " Meteorological Register, kept on board His 

 Majesty's Ship Thunder, between the 1st of January and the 30th of 

 June, 1834," by R. Owen, Commander. Communicated by Cap- 

 tain Beaufort, R.N., F.R.S. 



These observations relate to the state of the weather, the direction 

 and force of the wind, and the heights of the thermometer, and of the 

 marine and oil barometers. 



May 14, 1835. 



JOHN WILLIAM LUBBOCK, Esq., Vice-President and Trea- 

 surer, in the Chair. 



A paper was read, entitled, " An Account of the Water of the 

 Well Zem-zem, with a qualitative analysis of the same by Professor 

 Faraday" j in a letter from John Davidson, Esq., to the Secretaries, 

 and communicated by them. 



The author having, during his stay at Jedda, the port of Mecca, 

 succeeded in procuring about three quarts of the water from the well 

 of Zem-zem, to which the Mahomedans ascribe a sacred character 

 and extraordinary virtues ; and wishing to preserve this water for the 

 purposes of analysis, had the can in which it was contained carefully 

 sealed ; but, unfortunately, on its arrival in the London Docks, the 

 can, notwithstanding the directions written on it, was opened, and 

 the gas with which it was highly charged, and by which it held in solu- 

 tion a very large quantity of iron and other matters, was allowed to 

 escape. The precipitate thrown down, in consequence of the loss of 

 this gas, was found, by Professor Faraday, to consist of carbonate of 

 protoxide of iron in the enormous proportion of 100*8 grains to the 

 imperial pint of water. The clear fluid was neutral, and contained 

 much muriate, and a little sulphate, but no carbonate j together with 

 a little lime, potash, and soda. There was also found an alkaline ni- 



