GELLIBRAND, HENRY)( an industri ous English mathematician and astrono mer, was born at London in the year 1597. When he was eighteen years of age he was admitted a commoner of Trinity College, in the university of Ox ford, where, in the year 1619, he took his degree of B. A. At that time, An thony Wood says, " He was esteemed to have no great matter in him ;" but after wards he conceived a strong inclination for the mathematics, upon accidentally hearing one of Sir Henry Saville's lec tures in that science, and applied to it with considerable diligence and success. Having taken orders, he settled for some time as a curate at Chiddingstone in Kent ; but his passion for mathematical studies determined him to quit that situ ation, and to return to the University, where he might uninterruptedly pursue the bent of his mind, supported by the moderate private patrimony which de scended to him on the death of his father. His sole attention was now de voted to the mathematics, in which he made such proficiency, at the time of his taking his degree of M. A. in 1623, that he attracted the notice and friend ship of several able mathematicians who flourished at that time, particularly of the celebrated Henry Briggs, then Savil lian professor of geometry at Oxford. While he continued in the pursuit of these studies, the professorship of as tronomy in Gresham College, London, becoming vacant by the death of the in genious Edmund Gunter, Mr. Briggs en couraged Mr. Gellibrand to 'become a candidate for that chair. Accordingly he proceeded to London, with strong testimonials in his favour from the Presi dent, Vice President, and Fellows of his College, and other active friends, and was chosen to fill that post by the elec tors, in the month of January, 1626. From that time he lived, as he had done before, in a close intimacy with Mr. Briggs, who took great pleasure in com municating to him his mathematical opi nions and discoveries, and at the time of his death confided to him the task of completing his "British Trigonometry," which he did not live to finish. While Mr. Gellibrand was preparing that work for the press, he was cited, together with his servant 'William Beale, into the High Commission Court, by Doctor Laud, then Bishop of London, on account of an almanac for the year 1631, which Beale had published with the approbation of his master. In this almanac, the Popish saints usually put into the calendar were omitted, and the names of other saints and martyrs, mentioned in " Fox's Acts and Monuments of the Church," were inserted, as they stood in Fox's calendar. This circumstance gave great offence to the haughty prelate, and determined him to prosecute them for a measure, which he considered to be an unequivocal evi dence of their Puritanism. But when their cause came to a hearing, by shew ing that what they had done was no in novation, and pleading that they had no ill intention, they were acquitted by Archbishop Abbot and the whole court, Laud only excepted ; which was made an article of accusation against the last.men tioned prelate at his own trial. This prosecution proved the means of retard ing the publication of Mr. Briggs' work ; but when Mr. Gellibrand had escaped from the vengeance of Laud, he again applied to the completion of his friend's design, and having added to it a preface, and the application of the logarithms to plane and spherical trigonometry, &c.
constituting the second book of the work, the whole was printed at Gouda in Hol land, under the care of Adrian Vlacq, in 1636. It was entitled " Trigonornetria Britannica, sive de Doctrina Triangulo rum, Libri duo, &c." folio.
Mr. Gellibrand, however, though an industrious mathematician, had not suffi cient comprehension of mind to admit the evidence, which Galileo had lately pro duced in support of the Copernican sys tem. This appears from the account which he has given of a conversation which he had, when he went over to Holland on the business of printing the Trigonometry,with Lansberg,an eminent astronomer in Zealand, who insisted on the truth of that system. " This, which he was pleased to style a truth," says our author, " I should readily receive as an hypothesis, and so be easily led on to the consideration of the imbecility of man's apprehension, as not able rightly to conceive of this admirable opifice of God, or frame of the world, without falling foul of so great an absurdity. Yet, sure I am, it is a probable induce ment to shake a wavering understand ing." From Mr. Gellibrand's situation at Gresham College, and his intercourse with the lovers of mathematical studies, he had an opportunity of contributing some pieces, mentioned below, to the imp-ovement of navigation, which sci ence would probably have been farther benefitted by him, bad he not been imma turely carried off by a fever in 1636, when in the fortieth year of his age. That his mathematical knowledge was consider able, and usefully applied, is sufficiently apparent from the treatises which he left behind him, and the estimation in which he was held by the most respectable men of science among his contempora ries, both at Oxford and London. But he is entitled more to the praise of close and unwearied industry than of invention or genius. Besides his part of the " Tri gonometria Britannica," he was the au thor of" An Appendix concerning Longi tude," subjoined to Captain Thomas James's Voyage for the Discovery of the North West Passage, 1633, quarto ; " A Discourse mathematical, on the varia tion of the Magnetic Needle, together with the admirable diminution lately dis covered," annexed. to Wright's " Errors in Navigation Detected, &c." 1635, quarto ; "A preface to the Sciographia of John Wells, of Brembridge, Esq." 1635, 8vo ; "An Institution, trigonome trical, explaining the doctrine of plane and spherical Triangles, after the most exact and compendious way, by Tables of Si nes,Tangents,&c. with the application thereof to questions of Astronomy and Navigation," 1634, octavo ; and after wards republished with enlargements by Leybourn, 1652, octavo ; "An Epitome of Navigation, with the neces sary tables," &c. and " An Appendix con cerning the Use of the Quadrant, Fore staff, and Nocturnal," octavo ; " °ratio in Laudem Gassendi Astronomix, habits in Aula iEdis, Christi, Oxon ;" and of several unpublished MSS. on the Doc trine of Eclipses, Lunar Astronomy, Ship Building, &c.