In order to compare the different machines in respect to this theory, suppose we take, first, the Ordinary with a fifty-inch wheel and cranks, say, eight inches apart, or four inches from the centre of the wheel to either crank. Now, if the pedal _b_ (Fig. 1) is four inches long, the distance from the centre of the pedal to the centre of the axle of the drive-wheel is six inches, and the diameter of the wheel fifty inches; then, when the crank is extended horizontally out in front, this being the position when it is supposed to be subjected to the greatest strain, we have the following conditions (see Fig. 2): [Illustration: Fig. 1. Fig. 2. Side-slip diagrams.] Let _a b_ represent the distance of the centre of the wheel from the centre of the pedal, _a c_ the vertical height of the pedal from the ground, and _W_ the weight of the man. Then _W_ applied vertically downward at _b_ will create a horizontal side-slip pressure, _R_ at _ab_ _c_, in the direction of the arrow, such that _R_ = _W_ ————. If, _ac_ then, _W_ = 150 pounds and _a b_ and _a c_ = 6 and 25 inches 6 respectively, we have _R_ = 150 × —— = 36 pounds. Supposing the theory 25 to be correct, the above may be said to represent the side-slip resultant in the fifty-inch Ordinary. In the Kangaroo the cranks, being below the centre of the wheel, average about twelve inches from the ground when power is applied. The pedals are about a foot apart, so that _ab_ = 8, _ac_ = 12, and _W_ = 150, whence _R_ by the same formula equals one hundred pounds. The above, though perhaps slightly exaggerated in its application to some of the Kangaroo patterns, is substantially correct, showing the difference to be sixty pounds against it. According to this theory, then, the greater the tread and the less the distance of the pedals from the ground, the greater should be the side-slip.