[Illustration: Lever rear-driver, 30-inch wheels, gear about 50; up hill, grade, one foot in twenty; speed, eight miles per hour.] [Illustration: Lever rear-driver, 30-inch wheels, gear about 50; up hill, grade, one foot in twenty; speed, twelve miles per hour.] [Illustration: Lever rear-driver, 30-inch wheels, gear about 50; up hill, grade, one foot in twenty; continuation of No. 14, over top of hill.] A six-inch crank was used upon the machines in these experiments, and the lever action was such as to be comparable to a fifty-inch gear. The height of a point on the curve shows the extent of and variation in power upon the pedal, and the translation from left to right the time. In consequence of the limit of pressure occurring but once in each stroke, the number of undulations determines the speed, since it would show the number of strokes in a given time, and we know the number that make a mile. The number of pounds’ pressure at any point on a curve is shown by the figures upon the perpendicular line, as, for example, in No. 1 the apex of the curve just to the right of the scale is about even with the hundred-and-fifty-pound point; this pressure was maintained for a very short space of time, since the curve travels a very short distance to the right at this point; in other words, it is quite sharp at the top. Stronger springs were used on the Cyclograph in testing the safeties, as I found myself liable to compress them beyond their limit; hence the scales must be closely observed in making comparisons. Among the interesting results noticeable in these experiments I find, for instance, in Nos. 3 and 4, an abnormal deviation in the height of the curves at the same speed upon the same track at nearly the same time, though running in opposite directions. Finding this strange difference of some fifty pounds in pressure, I noticed an almost imperceptible breeze against me in the one, and in my favor in the other, direction. No. 12 illustrates how a hundred-and-fifty-pound man gets up a pressure of two hundred and forty pounds presumably by a ninety-pound pull on the handle-bar. In No. 9 we see how one hundred and fifty pounds pressure is applied in back-pedalling down a grade of one foot in twelve. That the curve would not be very regular is easily impressed upon the mind of the average rider. One part of curve (not shown), of peculiar contour, terminated experiment No. 9 at a rut a little farther down the hill, with dire results to the operator and provoking influence upon the running gear of the ’graph, which has been making some erratic curves of its own, now and then, ever since. Comparing Nos. 5, 10, and 13, the curve of the lever machine (13) indicates that, while pressure is not so great as in the others, it is held for a longer time, shown by the greater height and sharper tops to the curves of the crank machines.