The best books of reference on the subjects of this memoir are ‘Baron’s Life of Jenner,’ ‘Moore’s History of the Cow-pox,’ Dr. Gregory’s admirable articles in the ‘Encyclopædia of Medicine,’ and the reports of various parliamentary committees, especially those of 1802 and 1833. [Illustration] MASKELYNE. Nevil Maskelyne was born in London, October 6, 1732. He was educated at Westminster, and in time proceeded to Catherine Hall, Cambridge, from whence he migrated to Trinity College. He took the degree of Bachelor of Arts, with honours, in the year 1754. In 1755, he was ordained to a curacy near London. He had previously turned his attention to astronomy, to which he was led by the solar eclipse of 1748; and he now formed an acquaintance with Bradley, an astronomer of unequalled merit, whether in discovery or practical excellence in observation, whom he assisted in calculating his table of refractions. It is no wonder that, under such instruction, Maskelyne should have distinguished himself afterwards as an observer. From this period (A.D. 1750) Delambre dates the commencement of really good observations. In 1758 Maskelyne was elected Fellow of his college; in 1759 he became Fellow of the Royal Society. In 1761 he went to St. Helena, to observe the transit of Venus, and also to collect such observations as might, if possible, enable him to detect the parallax of the fixed stars. He failed in both objects; in the first from cloudy weather, in the second from faulty instruments, as he supposed, though the quantity in question is so small that its existence has not yet been detected; but he was enabled to correct the principal errors of those instruments in a considerable degree, and also to make very good observations on various other points. In his voyage out and home he applied himself to perfect the method of observing lunar distances, and deducing the longitude from them. In 1764 he sailed to Barbadoes, to make a trial of Harrison’s time-keeper; and in 1765 he was appointed Astronomer Royal, on the decease of Mr. Bliss. He was then only thirty-three years of age, and had enjoyed a rapid career of celebrity. He had published enough in the ‘British Mariner’s Guide,’ A.D. 1763, to require honourable mention of his name and methods in every work of navigation. [Illustration: _Engraved by E. Scriven._ MASKELYNE. _From the original Picture by Vanderburgh in the possession of the Royal Society._ Under the Superintendance of the Society for the Diffusion of Useful Knowledge. _London, Published by Charles Knight, Ludgate Street._ ]