congenial to his favourite pursuits. The latter, who held the important office of secretary to the Board of Longitude, died, and after this event a memorandum was found in his hand-writing, which he had deposited with Professor Rigaud, desiring that, on the event of his death, the Admiralty should be informed that no one was so competent, in his opinion, to succeed him as Mr. Henderson. The Admiralty were pleased to think otherwise, and appointed Mr.
Pond, the Astronomer-Royal, to the charge. Soon after another important vacancy occurred by the death of Mr. Fallows, who had charge of the observatory at the Cape of Good Hope; and on the Admiralty offering it to Mr. Henderson, he closed with the proposal, and repaired to the Cape in 1832, although it was to sojourn among strangers, and with a disease of the heart, which, he knew, might at any time prove fatal. His scientific exertions during his short residence at the Cape of Good Hope, attested his self-devoted zeal in behalf of astronomy; for, independently of his official duties, the mass of observations and calculations which he had stored up, would have sufficed for the lifetime of a less earnest astronomer. Such incessant labour proved too much for his constitution, and in little more than a year he was obliged to return home, where, fixing his residence in Edinburgh, he devoted himself to the task of arranging the large mass of valuable materials which he had collected at the Cape. While he was thus employed, an agreement was entered into, in 1834, between the
government and the Astronomical Institution of Edinburgh, by which the Institution agreed to give up the use of their observatory on the Calton Hill to the University, while the government engaged to convert it into a public institution, furnish it with suitable instruments, and provide for an observer and assistant. This movement made it necessary to fill up the professorship of practical astronomy, which had been vacant sixteen years; and on Lord Melbourne applying to the Astronomical Society of London for advice upon the subject, Mr. Henderson, was recommended to the chair, to which he was appointed, with the honorary office of Astronomer-Royal for Scotland, being the first that had held it. Having thus obtained a situation that realized the beau ideal of his ambition for scientific distinction, opportunities of study, and means
of comfort, he, in 1836, married Miss Adie, eldest daughter of Mr. Adie, the talented inventor of the sympiesometer.
Hitherto we have scarcely alluded to Professor Henderson's astronomical writings, upon which his fame depends. A list of these, however, amounting to upwards of seventy communications, has been published in the "Annual Report of the Astronomical Society for 1845." To these also must be added his five volumes of observations from the Calton Hill, which were made between the years 1834 and 1839, as well as the selections from them which were given to the world after his death. To all this labour, the exactness, and, in many cases, the originality of which is more wonderful than the amount, great as it was for so short a life, he brought that methodical diligence and application which he had acquired in youth at the desk of a writer, and through which he became a prosperous lawyer. It was not merely in astronomical calculation that he excelled ; the different departments of natural science also had occupied his studies, so that at different periods he was enabled to supply the places of the professors of mathematics and natural philosophy in the University of Edinburgh. His death, which was sudden, and occasioned by that disease of the heart under which he had laboured for years, occurred on the 23d of November, 1844.
