Robert Davidson, of Aberdeen, was probably the first to make an electrically propelled carriage large enough to carry passengers. This he did in 1839. His carriage could carry two persons when traveling over a fairly rough road, and though the prospects were enticing enough to cause investment in the enterprise, Davidson's subsequent work was on rail vehicles. W. G. HEATON W. G. and R. Heaton, of Birmingham, England, built several steam carriages which operated with various degrees of success in their neighborhood. Their patent was dated in October, 1830. The patent aimed particularly at the guidance of a locomotive carriage, and the management of the steam apparatus so that the power and speed might be accommodated to the nature of the road, the quantity of the load, and so on. For the purpose of steering the carriage, a vertical spindle was placed at some distance before the axle of the front wheels and on its lower end a small drum was fixed. Around this drum was coiled a chain with its middle fixed upon the drum, and its ends made secure to the front axle formed a triangle with the drum, situated at the angle opposite the longest side. The other end of the vertical spindle was connected with a frame situated in front of the coachman's or rather the steersman's seat and here on the spindle was a horizontal beveled-toothed wheel. Over this wheel an axis extended, terminating in two crank handles proceeding from the axes in different directions, so that one was down when the other was up. Upon this axis was fixed another beveled-toothed wheel taking into the first. When these wheels were turned in one direction the right-hand fore wheel of the carriage advanced and the coach turned towards the left, while when they were turned in the other direction the left-hand wheel advanced and the carriage turned towards the right. The driving wheels were connected with the axle by means of a pair of ratchets furnished with a double set of ratchet teeth and a reversing pall. By this one wheel could be advanced or backed while the other remained stationary, or moving in a contrary direction, an arrangement necessary for turning and backing. The steersman controlled the reversing pall by connecting rods and lever. Motion was communicated to the driving wheels by a double set of spur wheel gear, arranged to give different powers or velocities, by having both a large and a small wheel fixed on the driving as well as the driven axis. By shifting the large wheel on the driving axis into gear with the small wheel on the driven axis speed was obtained, and by shifting their relative position till the small wheel on the driving axis came into gear with the large wheel on the driven axis, power was obtained at the expense of speed. These two axes were kept at the same distance from each other by means of connecting rods, although the relative positions might be changed by the motion of the carriage on rough roads.