Part of a Letter from Sr. R. B. to Dr. L. concerning a New Sort of Calesh

Part of a Letter from Sr. R. B. to Dr. L. concerning a new sort of Calesh. Sr. William Petty, Mr. Molyneux and I have spent this day in making experiments, with a new invented Calesh, along with the Inventor thereof; 'tis he that was in London when I was there, but he never made any of these Caleshes there, for his invention is much improved since he came thence; it is in all points different from any machine I have ever seen: It goes on two wheels; carries one Person; is light enough: as for its performance, tho' it hangs not on Braces, yet it is easier than the Common Coach, both in the high way, in ploughed Fields, crofs the ridges, directly, and obliquely: a common Coach will overturn, if one wheel go on a superficies a foot and a half higher than that of the other, but this will admit of the difference of $3\frac{1}{2}$ foot in height of the superficies, without danger of overturning: we chose all the irregular Banks, and sides of Ditches to run over, and I have this day seen it at five severall times turn over and over, that is, the wheels so over-turnd as that their Spokes lye parallel to the Horizon, so that one wheel lies flat over the head of him that rides in the Calesh, and the other wheel flat under him, but so much I call but once overturnd. But what I have mentioned was another turn more, so that the wheels were again in Statu quo; and the Horse not in the least disordered. If the Horse should be in the least unruly, with the help of one pin, you disengage him from the Calesh without any Inconvenience. I myself have been once overturnd, and knew it not till I lookt up, and saw the wheel flat over my my head; and if a Man went with his Eyes shut, he would imagine himself in the most smooth way, tho' at the same time there be 3 foot difference in the height of the ground of each wheel. In fine, we have made so many and so various experiments, and are so well satisfied of the usefulness of the Invention, that we have each of us bespoken one; they are not (Plain,) above six or eight pound a piece, Dublin, May 5th, 1685.