Navy Yard. This task, in a novel department, required of him extraordinary skill, and was of the utmost responsibility. The experience and the exhaustive study which it involved found expression a few years later, in A Treatise on Terrestrial Magnetism and on the Magnetism of Iron Vessels, published by Van Nostrand, in 1877; a Revised Edition was published in 1883. At one time the Treatise was used as a text-book in The Naval Academy at Annapolis.
With zeal such as his in whatever his hand found to do, united with so much efficiency, executive ability, and prepossessing manners, it is small wonder that many an institution was eager to obtain his services on its executive board.
After having faithfully performed the duties of Professor of Civil Engineering in The University of Pennsylvania for fifteen years, he resigned the position in 1871, and was immediately elected to the Board of Trustees. Nine years later, when, through the resignation of Dr Stillé, the office of Provost became vacant, Professor Rogers (the honourable title still clung to him) was earnestly and unanimously requested by the Board of Trustees to accept the position. But he shrank from the weight of responsibility and the restricted liberty of action which its acceptance would entail, and declined the honour.
At about the same time that he resigned his Pro-
