the instrument associated with his name is described. He died at Ornans in 1637.
The instrument invented by Vernier is frequently called a nonius, particularly in Germany, after Pedro Nunez (1492–1577), professor of mathematics at the university of Coimbra; but this is incorrect, as the contrivance described by the latter in his work De crepusculis (1542) is a different one, although the principle is practically the same. Nunez drew on the plane of a quadrant 44 concentric arcs divided respectively into 89, 88, . . . . . 46 equal parts; and if the alidade did not coincide with one of the divisions on the principal arc, which was divided into 90 parts, the number of degrees in a quadrant, it would fall more or less accurately on a division line of one of the auxiliary arcs, from which the value of the measured angle could be made out. This instrument was, however, very difficult to make, and was but little used. Vernier proposed to attach to a quadrant divided into half-degrees a movable sector of a length equal to 31 half-degrees, but divided into 30 equal parts, whereby single minutes could be read off by seeing which division line of the "sector" coincided with a division line of the quadrant. The idea had been mentioned by Christopher Clavius (1537–1612) in his Opera mathematica, 1612 (ii. 5 and iii. 10), but he did not propose to attach permanently an arc divided in this way to the alidade; this happy application of the principle at all events belongs to Vernier.
The principle of the vernier is readily understood from the following account: Let AB (see fig.) be the normal scale, i.e. a scale graduated according to a standard of length, CD, a scale (placed in contact with AB for convenience) graduated so that 10 divisions equal 11 divisions of the scale AB, and EF a scale placed similarly and graduated so that 10 divisions equal 9 divisions of the scale AB. Consider the combination AB and CD. Obviously each division of CD is 116th greater than the normal scale division. Let a represent a length to be measured, placed so that one end is at the zero of the normal scale, and the other end in contact with the end of the vernier CD marked 10. It is noted that graduation 4 of the vernier coincides with a division of the standard, and the determination of the excess of α over 3 scale divisions reduces to the difference of 7 divisions of the normal scale and 6 divisions of the vernier. This is ·4, since each vernier division equals 1·1 scale division. Hence the scale reading of the vernier which coincides with a graduation of the normal scale gives the decimal to be added to the normal scale reading. Now consider the, scales AB and EF, and let β be the length to be measured; the scale EF being placed so that the zero end is in contact with an end of β. Obviously each division of EF is 116th less than that of the normal scale. It is seen that division 6 of the vernier coincides with a normal scale division, and obviously the excess of β over two normal scale divisions equals the difference between 6 normal scale divisions and 6 vernier divisions, i.e. 0.6. Thus again in this case the vernier reading which coincides with a scale reading gives the decimal to be added to the normal scale. The second type of vernier is that more commonly adopted, and its application to special appliances is quite simple. For example, the normal scale to an English barometer is graduated in 125ths of an inch. The vernier is such that 24 divisions of the normal scale equal 25 of the vernier; each of the latter therefore is .002 or 1500th inch less than the normal division. In the scientific barometer, the normal scale is graduated in millimetres, and the vernier so that 20 scale divisions equal 19 mm. This combination reads to 0.05 mm.
VERNIS MARTIN, a generic name, derived from a distinguished family of French artist-artificers of the 18th century, given to a brilliant translucent lacquer extensively used in the decoration of furniture, carriages, sedan chairs and a multitude of small articles such as snuff-boxes and fans. There were four brothers of the Martin family: Guillaume (d. 1749), Simon Etienne, Julien and Robert (1706–1765), the two first-named being the elder. They were the children of Etienne Martin, a tailor, and began life as coach-painters. They neither invented, nor claimed to have invented, the varnish which bears their name, but they enormously improved, and eventually brought to perfection, compositions and methods of applying them which were already more or less familiar. Oriental lacquer speedily acquired high favour in France, and many attempts were made to imitate it Some of these attempts were passably successful, and we can hardly doubt that many of the examples in the possession of Louis XIV. at his death were of European manufacture. Chinese lacquer was, however, imported in large quantities, and sometimes panels were made in China from designs prepared in Paris, just as English coats of arms were placed upon Chinese porcelain in its place of origin. Biographical details of the career of the brothers Martin are scanty, but we know that the eldest was already in business in 1724. Their method and work must have come rapidly into vogue, for in 1730 Guillaume and Simon Etienne Martin were granted by letters patent a twenty years' monopoly, subsequently renewed, of making "toutes sortes d'ouvrages en relief de la Chine et du Japon." At the height of their fame the brothers directed at least three factories in Paris, and in 1748 they were all classed together as a "Manufacture nationale."
One of them was still in existence in 1785. The literature of their day had much to say of the freres Martin. In Voltaire's comedy of Nadine, produced in 1749, mention is made of a berline "bonne et brillante, tous les panneaux par Martin sont vernis"', also in his Premier discours sur I'inSgalitS des conditions he speaks of " des lambris dores et vernis par Martin." The marquis de Mirabeau in U Ami des hommes refers to the enamelled snuff-boxes and varnished carriages which came from the Martins' factory. It is the fate of all the great artists of the past to have had their names attached, by popular rumour or interested artifice, to a multitude of works which they never saw, and the Martins have suffered considerably in this respect. That the quality of their production varied between very wide limits is established by existing and undoubted examples; but it is extremely improbable that even their three factories could have turned out the infinite quantity of examples that has been attributed to them. Yet their production was large and exceedingly miscellaneous, for such was the rage for their lacquer that it was applied to every possible object. Nor need we be surprised at a rage which was by no means confined to France. At its best Vernis Martin has a splendour of sheen, a perfection of polish, a beauty of translucence which compel the admiration due to a consummate specimen of handiwork. Every variety of the lacquer of the Far East was imitated and often improved upon by the Martins—the black with raised gold ornaments, the red, and finally in the wonderful green ground, powdered with gold, they reached the high-water mark of their delightful art. This delicate work, poudre and wavy-lined with gold or semi with flowers overlaid with transparent enamel, is seen at its best on small boxes, fans, needle-cases and such-like. Of the larger specimens from the Martins' factories a vast quantity has disappeared, or been cut up into decorative panels. It would appear that none of the work they placed in the famous hotels of old Paris is now in situ, and it is to museums that we must go for really fine examples—to the Musee de Cluny for an exquisite children's sedan chair and the coach used by the French ambassador to Venice under Louis XV.; to the Wallace collection for the tables with richly chased mounts that have been attributed to Dubois; to Fontainebleau for a famous commode. Even the decorations of the apartments of the dauphin at Versailles, executed, or at least begun, in 1749, have vanished; so have those at Bellevue. It has been generally accepted that of the four brothers Robert Martin accomplished the most original and the most completely artistic work. He left a son, Jean Alexandre, who described himself in 1767 as “Vernisseur du Roi de Prusse.” He was employed at Sans Souci, but failed to continue the great traditions of his father and his uncles. The Revolution finally extinguished a taste which had lasted for a large part of the 18th century. Since then the production of lacquer has, on the whole, been an industry rather than an art. (J. P.-B.)
VERNON, EDWARD (1684–1757), English admiral, was born in Westminster on the 12th of November 1684. He was the second son of James Vernon, secretary of state from 16971700, a scion of an ancient Staffordshire family who is best remembered by three volumes of his letters to the duke of Shrewsbury, which were published in 1841; and his mother was Mary, daughter of Sir John Buck of Lincolnshire. Edward Vernon was sent to Westminster school at the age of seven;
