Leonardo da Vinci in the fifteenth century anticipated many of the modern tools.[8] His sketches are fascinating and show a wonderful and fertile ingenuity, but, while we wonder, we smile at their proportions. Had not a later generation of mechanics arisen to re-invent and re-design these tools, mechanical engineering would still be as unknown as when he died. [8] _American Machinist_, Vol. 32, Part 2, pp. 821 and 868. Take the slide-rest. It is clearly shown in the French encyclopedia of 1772, see Fig. 3, and even in an edition of 1717. Bramah, Bentham and Brunel, in England, and Sylvanus Brown,[9] in America, are all said to have invented it. David Wilkinson, of Pawtucket, R. I., was granted a patent for it in 1798.[10] But the invention has been, and will always be, credited to Henry Maudslay, of London. It is right that it should be, for he first designed and built it properly, developed its possibilities, and made it generally useful. The modern slide-rest is a lineal descendant from his. [9] Goodrich: “History of Pawtucket,” pp. 47-48. Pawtucket, 1876. [10] _Ibid._, p. 51. Blanchard was by no means the first to turn irregular forms on a lathe. The old French rose engine lathe, shown in Fig. 4, embodied the idea, but Blanchard accomplished it in a way more mechanical, of a far wider range of usefulness, and his machine is in general use to this day. [Illustration: FIGURE 3. FRENCH SLIDE-REST, 1772] [Illustration: FIGURE 4. FRENCH LATHE FOR TURNING OVALS, 1772 The spindle swings sidewise under the influence of the two cams which bear against the upright stops] [Illustration: