Sir,—You have communicated to me, that the Royal Society of Sciences in Edinburgh has done me the honour to elect me as a corresponding member. I beg you to render my humble thanks to the Society, and to assure, that it shall be my earnest wish to fulfil every task in my power which the Royal Society should demand.

That this letter may not reach your hands without any scientific communication, I subjoin the following:—From November 1822 to April 1824 inclusive, I observed the height of the barometer in Christiania, and found the mean reduced to 0°R., and to the level of the sea =757m·763 = 335‴·913 lign. de Paris. As the mean height of the barometer observed at Paris by Bouvard, and reduced to 0°, and the level of the sea is = 337‴·53, I was surprised at the great difference of l‴·62 between Paris and Christiania. If p denotes the pressure of the atmosphere at the level of the sea, m and h the density of the mercury and its height in the tube, g the force of gravity, we have p = mgh, and, in another place, p′= mg′h′. If p′ = p is gh = g′h′, or h′ = . If, in the first place, the latitude is = ϕ, in the second, = ϕ′, we have ; h−h′ = h, 0·0025911 (cos 2 ϕ – cos 2 ϕ′). Taking ϕ = 0′, ϕ′ =90°, we have h−h′ = l′′′·74; and when ϕ = 48°·50′ (Paris), ϕ′ = 59°·55′ (Christiania), we have h−h′ = 0′′′·32. But the observations have given for Paris and Christiania h−h′ = l′′′·62; consequently, the mean pressure of the atmosphere is not the in different latitudes (“Magazin for Naturvidensk.” 1824, page 282–291).