[ 163 J 

 XXV. Proceedings of Learned Societies. 



ROYAL SOCIETY. 

 [Continued from vol. xix. p. 522.] 

 Nov. 18, rr^HE following papers were read : — 



1841. A. 1. " Variations de la declinaison et intensity mag- 

 netique horizontale observees a Milan le 28 et 29 Mai, le 23 et 24 

 Juin, le 21 et 22 Juillet, le 27 et 28 Aout, et le 22 et 23 Septembre 

 184.1." Par Sig^ Carlini, For. Memb. R.S. 



2. ■" Variations de la declinaison magnetique et de I'intensite mag- 

 netique horizontale observees a Bruxelles le 23 et 24 Juin, et le 21 

 et 22 Juillet 1841." Par M. A. Quetelet, For. Memb. R.S. 



3. " Meteorological Register kept on board the Earl of Hardvvicke, 

 during a voyage from London to Calcutta and back to London, 

 by Captain Alexander Henning." Communicated by Sir John F. 

 W. Herschel, Bart., F.R.S., &c. 



4. " Meteorological Register kept at Port Arthur, Van Diemen's 

 Land, by Deputy-Assistant-Commissary-General Lempriere, from 

 Feb. 1, 1840, to Feb. 1, 1841." Communicated by Captain Beau- 

 fort, R.N., F.R.S., Hydrographer to the Admiralty. 



5. " Term Observations of the Variation, Magnetic Declination, 

 Horizontal Intensity, and Inclination at Prague, for June, July, 

 August and September 1 84 1 ." By Professor Kreil. Communicated 

 by S. Hunter Christie, Esq., Sec. R.S. 



November 25. — The following papers were read, viz. — 



1 . " Explanation of the construction, positions, comparisons, and 

 times of observation, of the Meteorological Instruments at the Royal 

 Observatory, Greenwich, with which the Observations have been 

 made that are contained in the sheets of Meteorological Observa- 

 tions, forms 1 and 2, for each month from 1840 November to 1841 

 July, both inclusive, sent to the Royal Society in 1841, October 26." 

 By George Biddell Airy, Esq., M.A., F.R.S., Astronomer Royal. 



2. " On the Laws of the rise and fall of the Tides in the River 

 Thames." By George Biddell Airy, Esq., M.A., F.R.S., Astronomer 

 Royal. 



The conclusions arrived at by the author, and stated in this paper, 

 were derived from an extensive series of observations of the tides, 

 made, on his suggestion, at the Royal Victualling Yard at Deptford, 

 under the superintendence of Captain Shireff, R.N. The object of 

 the first series of obser\'ations was simply to ascertain the times of 

 high and low water, foi' the purpose of ascertaining the duration of 

 the rise and fall of the tide : the height of the water was observed at 

 every quarter of an hour, night and day, during half a lunation. The 

 curves representing the law of rise and fall of the water were found 

 to be diti'erent for high tides and for low tides ; and both are sensibly 

 different from the line of sines. The author then investigates ma- 

 thematically the motion of a very long wave, such as a tide-wave, in 

 a rectangular canal, whose section is everywhere the same, on the 

 supposition that the extent of vertical oscillation bears a sensible 

 proportion to the mean depth of the water ; and deduces an expres- 

 M 2 



