He was a rugged, straightforward, kindly man, of great inventive power. He improved nearly everything he touched or superseded it entirely by something better, and neither his name nor his work should be forgotten. CHAPTER VI GEARING AND MILLWORK By 1830 the use of machine tools was becoming general; they were being regularly manufactured and their design was crystallizing. It was the period of architectural embellishment when no tool was complete without at least a pair of Doric columns, and planers were furnished in the Greek or Gothic style. As the first machine frames were made of wood, much of the work probably being done by cabinet makers, it was natural that they should show the same influence that furniture did. It took several generations of mechanics to work out the simpler lines of the later machines. The application of scientific forms for gear teeth came at about this time with the general development of the machine tool. The suggestion of the use of epicyclic and involute curves is much older than most of us realize. The first idea of them is ascribed to Roemer, a Danish mathematician, who is said to have pointed out the advantages of the epicyclic curve in 1674. De la Hire, a Frenchman, suggested it a few years later, and went further, showing how the direction of motion might be changed by toothed wheels. On the basis of this, the invention of the bevel-gear has been attributed to him. Willis,[60] however, has pointed out that he missed the essential principle of _rolling_ cones, as the conical lantern wheel which he used was placed the wrong way, its apex pointing away from, instead of coinciding with, the intersection of the axes. De la Hire also investigated the involute and considered it equally suitable for tooth outlines. Euler, in 1760, and Kaestner, in 1771, improved the method of applying the involute, and Camus, a French mathematician, did much to crystallize the modern principles of gearing. The two who had the most influence were Camus and Robert Willis, a professor of natural philosophy in Cambridge, whose name still survives in his odontograph and tables. All of the later writers base their work on the latter’s essay on “The Teeth of Wheels,” which appeared originally in the second volume of the “Transactions of the Institution of Civil Engineers,” 1837. Willis’ “Principles of Mechanism,” published in 1841, which included the above, laid down the general principles of mechanical motion and transmission machinery. In fact, many of the figures used in his book are found almost unchanged in the text-books of today. Smeaton is said to have first introduced cast-iron gears in 1769 at the Carron Iron Works near Glasgow, and Arkwright used iron bevels in 1775. All of these, except the last two, were mathematicians; and no phase of modern machinery owes more to pure theory than the gearing practice of today. [60] “Principles of Mechanism,” p. 49. London, 1841.