Cambridge Philosophical Society
The London Edinburgh and Dublin Philosophical Magazine and Journal of Science
After various presents of books and objects of natural history had been announced, a Memoir was read by the Rev. R. Murl)hy, '" On the Resolution of Equations of Finite Differences." Extracts were then read of letters from Sir J. Herschel to the Rev. W. SVhewell, containing various meteorological observations, and especially some tendin~ to show that the height of the barometer at the equator is less by about a quarter of an inch than it is at twenty or thirty degrees from it. The following are
... a porlion of the extracts here referred to : "The barometer certainly has a permanently and very decidedly lower mean level at and near the line. The strong upward current due to the circulation of the trades can alone account for this. Of the general fact I have no doubt, and however difficult it is to observe the barometer on shipboard, from the unusual quietness of our passage, I think I can come pretty, near to its true difference from that in our latitudes. The depressmn at the equator below that in lat. 20 ° may I think be stated at 0"2 nearly. "These are the results of a series of, barometrical observations, made at my request by Sir E. Ryan, in his voyage to Calcutta from this place. The barometer is reduced to 82 ° F., and to the Royal ,Society's Standard, by careful comparison with my Troughton's barometer.