(Peter), an ingenious naturalist, and member of several learned societies, was born at Maastricht, and was descended from a very ancient and respectable family of Lorraine. He had scarcely attained his seventh year before he displayed an uncommon strength and agility in all bodily exercises; but he was not less diligent in the improvement of his mind. Being placed at the Latin school, he learned chronology, and exercised himself in Latin, Greek, and French poetry, as also in Hebrew, logic, and the Cartesian Physics. He was particularly fond of the study of languages, whereof he understood no less than nine, living and dead. Having entered the university of Leyden, he studied the Newtonian philosophy, geometry, algebra, &c.; but his father (who was a clergyman), desiring he should attach himself to divinity, he reluctantly abandoned the former studies, as his passion for them was not easily to be overcome. He at the same time applied himself to anatomy, and also to music and drawing. He began afterwards to practise sculpture; and performed several pieces in wood, some of which are preserved, and have been greatly admired by the artists. After this, he betook himself to drawing portraits of his friends from life; wherein, after three or four months practice, he became a great proficient. Having attained the degree of candidate in divinity, he resolved to study law, to which he applied himself with so much zeal, that he was promoted at the end of the first year. Arrived at the Hague, he undertook the study of deciphering; and became secretary of the cyphers, translator of the Latin and French Languages, and patent-master, to their High Mightinesses. Meanwhile, having taken a strong liking to the study of insects, he undertook an historical description of such as are found about the Hague, and to that end collected materials for several volumes; and having invented a method of drawing adapted thereto, he enriched this work with a great number of plates, universally admired by all the connoisseurs who had seen them. In the year 1742 was printed at the Hague a French translation of a German work, the 'Theology of Insects,' by Mr Leffler. Love of truth engaged Mr Lyonet to defer the publication of his above-mentioned description, and to make some observations on that work, to which he has added two most beautiful plates, engraved from his designs. This performance caused his merit to be universally known and admired. The celebrated M. de Reaumur had the above translation reprinted at Paris, not so much on account of the work itself as of Mr Lyonet's observations; and bestowed on it, as did also many other authors, the highest encomiums. He afterwards executed drawings of the fresh-water polypus for Mr Trembley's beautiful work, 1744. The ingenious Wandelaar had engraved the first five plates; when Mr Lyonet, who had never witnessed this operation, concerned at the difficulties he experienced in getting the remaining eight finished in the superior style he required, resolved to perform the task himself. He accordingly took a lesson of one hour of Mr Wandelaar, engraved three or four small plates, and immediately began upon the work itself, which he performed in such a manner as drew on him the highest degree of praise, both from Mr Trembley and from many other artists, particularly the celebrated Van Gool; who declared that the performance astonished not only the amateurs, but also the most experienced artists. In 1748 he was chosen member of the Royal Society of London. In 1749 he began (by mere chance) his amazing collection of horns and shells, which, according to the universal testimony of all travellers and amateurs who have visited it, is at present the most beautiful, and certainly one of the most valuable, in Europe. In 1753 he became member of the newly-established Dutch Society of Sciences at Haarlem; and in 1757, after the celebrated M. le Cat, professor in anatomy and surgery, and member of almost all the principal societies in Europe, had seen Mr Lyonet's incomparable Traité Anatomique de la Chenille qui rouge le Bois de Saule, with the drawings belonging to it (which work was afterwards published), he was elected member of the Royal Academy of Sciences of Rome, whereof M. le Cat was perpetual secretary. After the publication of this treatise, he became, in 1760, member of the Royal Academy of Sciences of Berlin; in 1761, of the Imperial Academy of Sciences of St Petersburg. In order to enable such as might be desirous of following him in his intricate and most astonishing discoveries respecting the structure of this animal, Mr Lyonet published, in the Transactions of the Dutch Society of Sciences at Haarlem, a description and a plate (as he also afterwards did in French at the beginning of his Traité Anatomique) of the instrument and tools he had invented for the purpose of dissection, and likewise of the method he used to ascertain the degree of strength of his magnifying glasses. Notwithstanding all this labour, which was considerably increased by the extensive correspondence which he for many years carried on with several learned and respectable personages, he still found means to Concerning the number of strings with which this Lyre instrument was furnished, there is great controversy. Some assert it to be only three; and that the sounds of the two remote were acute, and that of the intermediate one, a mean between those two extremes: that Mercury, the inventor, resembled those three chords to as many seasons of the year, which were all that the Greeks reckoned, namely, Summer, Winter, and Spring: assigning the acute to the first, the grave to the second, and the mean to the third.

Others assert that the lyre had four strings; that the interval between the first and the fourth was an octave; that the second was a fourth from the first, and the fourth the same distance from the third, and that from the second to the third was a tone.

Another class of writers contend that the lyre of Mercury had seven strings. Nicomachus, a follower of Pythagoras, and the chief of them, gives the following account of the matter: "The lyre made of the shell was invented by Mercury; and the knowledge of it, as it was constructed by him of seven strings, was transmitted to Orpheus: Orpheus taught the use of it to Thamyris and Linus; the latter of whom taught it to Hercules, who communicated it to Amphion the Theban, who built the seven gates of Thebes to the seven strings of the lyre." The same author proceeds to relate, "That Orpheus was afterwards killed by the Thracian women; and that they are reported to have cast his lyre into the sea, which was afterwards thrown up at Antissa, a city of Lesbos: that certain fishers finding it, they brought it to Terpander, who carried it to Egypt, exquisitely improved, and, showing it to the Egyptian priests, assumed to himself the honour of its invention."

This difference among authors seems to have arisen from their confounding together the Egyptian and the Grecian Mercury.—The invention of the primitive lyre with three strings was due to the first Egyptian Hermes, as mentioned under that article.—The lyre attributed to the Grecian Mercury is described by almost all the poets to be an instrument of seven strings. See Mr Vincenzo Galilei has collected the various opinions of the several Greek writers who have mentioned the invention of the chelys or testudo; and the late Mr Spence has done the same in a very circumstantial but ludicrous manner. Horace talks of Mercury as a wonderful musician, and represents him with a lyre. There is a ridiculous old legend relating to this invention, which informs us, that Mercury, after feeding some bulls from Apollo, retired to a secret grotto, which he used to frequent, at the foot of a mountain in Arcadia. Just as he was going in, he found a tortoise feeding at the entrance of his cave: he killed the poor creature, and, perhaps, ate the flesh of it. As he was diverting himself with the shell, he was mightily pleased with the noise it gave from its concave figure. He had possibly been cunning enough to find out, that a thong pulled taut and fastened at each end, when struck by the finger, made a sort of musical sound. However that was, he went immediately to work, and cut several thongs out of the hides he had lately stolen, and fastened them as tight as he could to the shell of this tortoise; and, in playing with them, made a new kind of music with them to divert himself in his leisure."