LEX 



718 



LEY 



Lexell. would undoubtedly be found to be extensive, if the 

 ^"Y""*' shores were accurately examined; but, in other respects, 

 the flora of Harris is very meagre. See Martin's De- 

 scription of the Western Islands of Scotland ; Bucha- 

 nan's Travels in the Western Islands ; but particularly 

 M'Donald's Agricultural Survey of the Hebrides. 



LEXELL, ANDREW, JOUN, an eminent mathemati- 

 cian and astronomer, was born at Abo in Finland, on the 

 24th December, 1 740. He went through his early studies 

 in that town, and applied himself eagerly to the abstract 

 sciences. In 1760, he took his degree of doctor in phi- 

 losophy, and published an inaugural dissertation, enti- 

 tled, Apltorismi Mathematico-Physici, after having dis- 

 puted under the presidency of M. J. Gadolina, profes- 

 sor of natural philosophy. 



In 1763, M. Lexell repaired to Upsal, where he dis- 

 tinguished himself by a disputation, entitled, De Me- 

 thodo inveniendi lineas curvas ex dalis' radiorum oscttli 

 proprietatibuf, which obtained for 1iim the situation of 

 lecturer in mathematics ; and such was his reputation, 

 that, in 1766, he was appointed professor to the corps 

 of marine cadets. 



In consequence of the arrival of Leonard Euler at 

 St. Petersburg!!, and the preparations which were mak- 

 ing, in 1769, to observe the transit of Venus in eight 

 different parts of the Russian empire, M. Lexell became 

 anxious to reside in a capital containing such attractions 

 for men of science, and where genius and industry ne- 

 ver failed to meet with their reward. With this view, 

 he had sent to the academy, in 1768, a memoir on 

 the integral calculus, entitled, Me/hodus integrandi noa- 

 nullis eequationum exemplis illustrata. Euler was charg- 

 ed with the examination of this memoir, and gave a 

 very favourable report upon it. The Count Wolodi- 

 mer Orloff, however, who was then director of the aca- 

 demy, stated his suspicion that it might be the work of 

 some able geometer, who wished to favour Lexell by 

 his assistance ; to which Euler replied, that, if this 

 were the case, it must have been written either by 

 D'Alembert or himself, and that Lexell was unknown 

 to both. 



The Count, satisfied with this high eulogium on the 

 merits of Lexell, did not hesitate a moment in sending 

 to him an appointment of adjunct in the Academy for 

 the Mathematical Sciences. Lexell eagerly accepted of 

 the situation; and on the 17th October, 1768, he ob- 

 tained the consent of the Swedish government, and 

 set off without delay for St. Petersburgh. Upon his ar- 

 rival in that capital, he began to make himself familiar 

 with the use of astronomical instruments, in order that 

 he might be' able to observe with success the transit of 

 Venus ; a duty which he performed to the satisfaction 

 of the academy, along with Father Meyer, who had 

 been appointed, along with him, to attend the observa- 

 tory during the absence of the astronomers. M. Lex- 

 ell became very intimate with Euler, who employed 

 him in writing out all the calculations and memoirs 

 with which he was occupied. Lexell had also a consi- 

 derable share in the new theory of the moon, and in the 

 determination of the surf's parallax, as deduced from 

 the observations of the transit of Venus, which are 

 published in the 14th volume of the New Commenta- 

 ries of St. Petersburgh. 



The reputation of M. Lexell now increased every 

 day. In 1771> he was received among the number of 

 ordinary academicians, and Count Orloff gave him the 

 place of one of the astronomers. The academies of 

 Stockholm and Upsal elected him a member of their 

 body, in 1773 and 1774; and the Royal Academy of 

 Sciences of Paris sent him the diploma of correspond- 



ing member, in 1776. In 1775, the King of Sweden 

 conferred upon him the situatioij of professor of mathe- 

 matics in the university of Abo, with permission to re- 

 main three years in St. Petersburgh , a period <rhich 

 was twice prolonged for a year, till 1750. M. Lexell 

 was now upon the eve of quitting St. Petersburgh, and 

 of settling himself in his native town ; and the academy 

 would soon have lost his talents, had not M. de Domasch- 

 nef offered him leave to undertake a literary voyage 

 through Germany. France, and England, and to return 

 by Sweden to St. Petersburgh. M. Lexell undertook 

 the task, and returned to St. Petersburgh in the course 

 of a year, (in 1781,) highly satisfied with his journey. 



In 1733, the Princess Daschkaw gave him the place 

 in the academy which had been vacated by the death of 

 Euler, and besides added considerably to his appoint- 

 ments. The Royal Academy of Sciences of Turin re- 

 ceived him in the same year among the number of its 

 foreign associates ; and the English Board of Longi. 

 tude, in 1784, put his name in the list of philosophers 

 to whom> they sent all the works which they published 

 relative to the determination of the longitude at sea. 

 M. Lexell, however, did not live long to enjoy these 

 honours. He was seized with an illness before the win- 

 ter of 1784, and he died on the 30th November of that 

 year, in the 40th year of his age, of a gangrenous tu- 

 mour, followed by a malignant fever. 



Besides the works we have mentioned, M. Lexell 

 published, in the Philosophical Transactions for 1775, 

 a paper on the occultation of stars, and on two curious 

 theorems respecting polygons, which were communi- 

 cated in a letter to Dr. Morton. In the same work 

 for 1777, he published a paper " On the Periodic Time 

 of the Comet of 1770," which he stated at 5^ years. 



When theGeorgium Sidus was discovered, he set him- 

 self eagerly to observe its motions; and, in 1782, he 

 published at St. Petersburgh a small work, entitled, Re- 

 ckerches sur la Nouvelle Planete, where he attempted to 

 compute its motions, upon the supposition that it mov- 

 ed in an orbit nearly circular ; and he has shewn, that 

 a circular orbit whose radius is about nineteen times 

 the distance of the earth from the sun, will nearly re- 

 present all the observations made in 1781. His papers 

 in the Memoirs of the Academy of St. Petersburgh, be. 

 tween 1768 and 1784, amount to about fifty-six. They 

 are principally on mathematical and astronomical sub- 

 jects. 



LEYDEN, the LugduiiMn Batavorum of Ptolemy, is a 

 town of Holland, and next in importance and popula- 

 tion to Amsterdam. It is situated on the ancient bed 

 of the Rhine, which divides the town into a number of 

 islands, connected by bridges, which amount to nearly 

 100. The principal street, which is reckoned one of 

 the finest in Europe, is built in the form of a crescent. 

 The most important public buildings are, the church 

 of St. Peter, and the town-house. The church is esr 

 teemed one of the handsomest in Holland. It contains 

 the tomb of the great Boerhaave, with the simple in- 

 scription of Salultfero Boerhavii genio sacrum, and also 

 the tombs of P. Camper and Meerman. The town- 

 house has many spires, and is a handsome building, 

 with a stone front. A very capital painting of the last 

 judgment, by Lucas of Ley den, is preserved in the 

 burgomasters' chamber. The other public buildings 

 are the> observatory, and the chateau, which commands 

 a magnificent view. The subterraneous sewers of Ley- 

 den are ranked among the curiosities of the place. One 

 of them is about a quarter of a league long, and re- 

 ceives the boats, for the purpose of cleaning them. 



The university was founded in 1575, by William, 



LexcU, 



Lej'den. 



