xlvi REPORT. 1851. 



lution, and with the full hope that at some future time a confederation similar 

 to that proposed by M. Kupffer may be firmly established. 



Under the auspices of the Board of Ordnance, the officers of the corps of 

 Royal Engineers are making arrangements for the establishment of a uniform 

 system of meteorological observations, of a simple kind, at the principal en- 

 gineers' stations in every part of the earth. If with these could be combined 

 occasional trustworthy observations at sea, we should probably have the most 

 complete system of Terrestrial Meteorology that we can hope to obtain. 



Among systematic observations of less ostentatious character, I cannot 

 omit referring to the daily report of the state of the wind at 9 o'clock every 

 morning, which is supplied by the superintendents of railway stations, over a 

 great portion of the British Isles, and printed in the Daily News newspaper. 



A new Meteorological Society has been formed, which (I believe) is at 

 least in this respect superior to those which have preceded it — that the in- 

 struments used by the various amateur members are strictly comparable : 

 great attention having been given to the adjustments of the instruments, by 

 the Secretary, Mr. Glaisher. 



In Optics, two or three investigations of rather important character have, 

 since the last meeting of the Association, attracted public attention. Expe- 

 rimental measures of the velocity of light in air and in water, made by MM. 

 Foucault, Fizeau and Breguet, with apparatus nearly similar to that em- 

 ployed long ago for analogous purposes by Mr. Whealstone, appear to leave 

 no doubt tliat the velocity in water is less than that in air, — a most import- 

 ant, and indeed critical, result in regard to theories of light. A remarkable 

 investigation by Prof. Stokes, when compared with experiment, seems to 

 establish that the vibrations constituting polarized light are, as for other 

 reasons was supposed by Fresnel, perpendicular to what is usually called the 

 plane of polarization. Some optical theories which admitted formerly of 

 very imperfect mathematical treatment have been brought under the domi- 

 nion of analysis by Prof. Stokes's powerful methods of investigation. A 

 curious series of experiments on diffraction has been i^ublished by Lord 

 Brougham ; but they have at present no bearing on theory, as the theoretical 

 calculations with which they must be confronted appear to be too difficult 

 or too complicated for the present state of pure mathematics. The experi- 

 ments of Jamin regarding the reflexion of polarized light under peculiar 

 circumstances appear to give support to the theoretical calculations of Cauchy, 

 founded on a molecular hypothesis applied to the undulatory theory. And 

 lastly, some curious experiments by Masson, Jamin, Prevostaye, and Desains, 

 appear to show more fully, what had partially been shown by Prof. Forbes, 

 that radiant heat admits of polarization in all respects similar to that of light. 



I hope that we shall receive at this meeting, or shortly, two Reports on 



