Autograph letter signed to Archibald Smith

James, Henry (1803-77). Autograph letter signed to Archibald Smith. 4pp. London, November 8, 1864. 184 x 117 mm. Fine.

From Sir Henry James, director-general of the Ordnance Survey (the British government mapping agency), to Scottish lawyer and mathematician Archibald Smith, best known for his work on magnetism and the Earth's magnetic field, particularly in relation to navigation. James' letter discusses the survey of Jerusalem (then part of the Ottoman Empire) which was being performed by the Ordnance Survey for the purpose of improving the city's water supply and sanitary services (the results of this survey were published in 1865 under the title Ordnance Survey of Jerusalem). Smith was an advocate of the Royal Society's proposal that pendulum measurements of the Dead Sea elevation be taken during this survey; James replied as follows:

" . . . As regards the proposal of the Royal Society, which you have recommended them to support, to have pendulum observations taken in the Valley of the Dead Sea, I need not say how fully I recognize the interest and importance of having such observations taken, but we have not one with the present party, who without special instruction and training could take the observations, and if there was any one so qualified, we should have no funds out of which the cost of taking them could be paid. I think the present is a most favorable time for having the exact difference of level taken between the Mediterranean and the Dead Sea . . . But if anything is to be done, no time must be lost, as it is necessary that the observers and instruments should be at Jerusalem before the survey is finished, and before the hot weather returns . . .

"If the Council of the Royal Society, with the concurrence of the Astronomer Royal, should memorialize the Lords of H. M. Treasury to avail themselves of this opportunity for getting these important observations made, I think it very probable their consent and the necessary funds would be granted."

Smith's advocacy of the Jerusalem pendulum project evidently paid off: The Royal Society and the Royal Geographical Society each contributed £100 towards the cost of the pendulum work and the Ordnance Survey team was able to make accurate measurements of the difference between the levels of the Mediterranean and the Dead Sea (see Wilson). Wilson, Charles W., "Excerpts from the Ordnance Survey of Jerusalem." www.templemount.org. N.p., 21 Oct. 1996. Web. Accessed 31 October 2013.