Autograph letter signed to George W. Keely

Sabine, Edward (1788-1883). Autograph letter signed to George Washington Keely (1803-78). 7pp. Woolwich, October 2, 1846. 179 x 113 mm. Fine.

From Edward Sabine, one of the key figures in research on terrestrial magnetism in the 19th century. At the behest of the British government, Sabine established a system of magnetic observatories throughout the British Empire and spent much of his life analyzing the data they produced; his efforts resulted in the most complete magnetic survey of the globe as was then technically possible. His correspondent was George Washington Keely, professor of mathematics and natural philosophy at Waterbury (now Colby) College in Maine, who also worked on the U. S. Coast Survey in the 1850s.

Sabine had apparently agreed to help Keely purchase a magnetic surveying instrument known as a dip circle, and much of the letter is concerned with this transaction:

"I only rec'd your dip circle from Mr. Barrow a few days ago: one has to wait a very long time if one desires to have an instrument finished under the eye of the Artist himself . . . I think you will find reason to be much pleased with it: the microscopes are not adjusted to focus, but that is a small matter for you to do: the axles of the handles seem very perfect, & are very hard, so that they will not soon be worn out. There are two pairs, one pair for the dip; the other pair for the total intensity by Dr. Lloyd's statical method. You will find these extremely useful in your excursions . . . Captain Lefroy has taken charge of the instrument & will deliver it to Professor Renwick of Columbia College to whom you will be so good as to send your directions for its being forwarded . . . Captain Lefroy will also give Mr. Renwick for you a copy of the magnetic survey which we have just printed of a portion of your continent. It is done on the large scale and will of course admit of separate parts being carried out with a greater precision—this is particularly the case with the region north of you to the St. Lawrence, and East to the Atlantic . . ."

"Mr. Barrow" refers to instrument maker Henry Barrow (1790-1870); "Dr. Lloyd" refers to Irish physicist Humphrey Lloyd (1800-1881), provost of Trinity College, Dublin and head of the College's magnetic observatory. "Capt. Lefroy" refers to John Henry Lefroy (1817-90), who worked under Sabine supervising magnetic observatories in Canada and surveying the magnetism of the Canadian northwest. "Professor Renwick" refers to James Renwick (1790-1863), professor of natural history at Columbia College, New York and author of several widely used textbooks on natural philosophy, chemistry and mechanics.