368 Royal Societi/ : — 



Replies in some degree of detail have been received from five of 

 these gentlemen*, copies of which are herewith transmitted. 



The President and Council are glad to avail themselves of this 

 opportunity of expressing their acknowledgements to these gentle- 

 men, and more particularly to Professor Dove, Director of the Me- 

 teorological Establishments and Institutions in Prussia, whose zeal 

 for the advancement of Meteorology induced him to repair personally 

 to England, and to join himself to the Committee by whom the 

 present reply has been jn-epared. Those who are most familiar with 

 the labours and writings of this eminent meteorologist will best be 

 able to appreciate the value of his co-operation. 



The President and Council have considered it as the most con- 

 venient course to divide their reply under the different heads into 

 which the subject naturally l)ranches. But before they proceed to 

 treat of these, they wish to remark generally, that one of the chief 

 impediments to the advancement of Meteorology consists in the very 

 slow progress which is made in the transmission from one country to 

 another of tlie observations and discussions on which, under the 

 fostering aid of different Governments, so much labour is bestowed in 

 Europe and America ; and they would therefore recommend that 

 such steps as may appear desirable should be taken by Her Majesty's 

 Government, to promote and facihtate the mutual interchange of 

 Meteorological publications emanating from the Governments of 

 different countries. 



Barometer. 



It is known that considerable differences, apparently of a perma- 

 nent character, are found to exist in the mean barometric pressure 

 in different places ; and that the periodical variations in the pressure 

 in different months and seasons at the same place, are veiy different 

 in different i)arts of the globe, both as respects period and amount ; 

 insomuch that in extreme cases, the variations have even opposite 

 features in regard to period, in places situated in the same liemi- 

 si)here and at equal distances from the equator. 



For the purpose of extending our knowledge of the facts of these 

 departures from the state of equilibrium, and of more fully investi- 

 gating the causes thereof, it is desirable to obtain, by means of 

 barometric observations strictly comparable with each other, and 

 extending over all parts of the globe accessible by land or sea, 

 tables, showing the mean barometric pressure in the year, in each 

 month of the year, and in the four meteorological seasons, — on land, 

 at all stations of observation, — and at sea, corresponding to the 

 middle points of spaces bounded by geographical latitudes and longi- 

 tudes, not far distant from each other. 



The manner of forming such tables from the marine observations 

 which are now proposed to be made, by collecting together observa- 

 tions of the same month in separate ledgers, each of which should 

 correspond to a geographical space comprised between specified 



* Dr. Erman of Berlin; Dr. Heis of Miinstcr; Prof. Krcil of Vienna; Lieut. 

 Maury of Washington ; and M. Quetelet of Brussels. 



