P?'oceedings of the British Association. 311 



to be used in the construction of the new catalogue of the Astro- 

 nomical Society. No money has been spent during the year ; but 

 of course, a renewal of the grant will be desirable. — Signed for 

 the committee, J. P. W. Herschel. 



Report on the reduction of Meteorological Observations made 

 at the equinoxes and solstices, on the part of a committee appoifited 

 in 1838. — Sir J. Herschel, referring to his report of last year for 

 the reasons why the reduction of these observations was not im- 

 mediately commenced, reports further that the same reasons de- 

 layed, any effective commencement of the work until very lately ; 

 but that owing to several wanting series of observations having 

 at length come to hand, so as to render the series for the years 

 1835-8 tolerably consecutive, at least for several localities, your 

 Committee considered it advisable to wait no longer, but proceed 

 to work with the materials in hand. Accordingly, having cast 

 the plan of operations for the comparison and projection of the 

 barometric oscillations in those years, (to which for the present, 

 your Committee propose to limit their proceedings, till it shall ap- 

 pear whether a farther and more complete comparison, including 

 the thermometric changes, and especially the correspondence of 

 the winds, seems likely to lead to any valuable conclusions,) the 

 reduction, arrangement and projection of the several series of 

 observations was confided to the able and zealous hands of W. R. 

 Birt, Esq., who is now actively employed in this operation, and 

 who has enabled your Committee to lay before the meeting, as 

 specimens of the mode of proceeding, the tabulation and projec- 

 tion of the observations made in the British Isles in the year 

 1836, which are, accordingly, submitted for inspection. In the 

 discussion of these observations, it has been found advantageous 

 to divide the stations from which they have emanated, into groups, 

 according to geographical proximity, the chief of which are, — 

 the group of the British Isles, that of the continent of Europe, the 

 North American, South African and Indian groups. Each of 

 these groups is referred, by applying the differences of longitude 

 to the times of observation, to a central station ; and the projected 

 curves, in which the abscissae are the mean times at that station, 

 and the ordinates the reduced barometric altitudes, exhibit at one 

 view the correspondence or disagreement of the barometric move- 

 ments for all the stations of the group. * * * The projection of 

 these curves is the first step in the process of reduction con tern- 



