Sir James C. Anderson became associated with James, and in 1829 they built another carriage. This weighed nearly three tons, and the first trials were made round a circle of one hundred and sixty feet in diameter. When it was finally ready to be brought out it was loaded with fifteen passengers and driven several miles on a rough gravel road across Epping Forest, with a speed varying from twelve to fifteen miles an hour. Steam was supplied by two tubular boilers, each forming a hollow cylinder four feet six inches long. The tubes of which the boilers were composed were common gas pipe, one of which split on one of the trips, thus letting the water out of one of the boilers and extinguishing its fire. Under these circumstances, with only one boiler in operation, the carriage returned home at the rate of about seven miles an hour, carrying more than twenty passengers--at one period, indeed, it is said, a much greater number; showing that sufficient steam could be generated in such a boiler to be equal to the propulsion of between five and six tons weight. In consequence of this demonstration that the most brilliant success was attainable, the proprietors dismantled the carriage and commenced the construction of superior tubular boilers with much stronger tubes. Shortly after Anderson and James commenced to build another steam carriage, which was ready for use in November, 1829. This engine was not intended to carry passengers, but to be employed for drawing carriages behind. Four tubular boilers were used, the total number of tubes being nearly two hundred. These boilers were enclosed in a space four feet wide, three feet long, and two feet deep. The steam from each boiler was conducted into one main steam pipe one and one-half inches in diameter, and the communication from any one of the boilers could be cut off in case of leakage. Four cylinders, each two and one-quarter inch bore and nine inch stroke, were arranged vertically in the hind part of the locomotive, and two of them acted upon each crank-shaft as before, giving a separate motion to each driving wheel. The exhaust steam was conducted through two copper tanks for heating the feed water to a high temperature, and thence passed to the chimney. The steering-gear consisted of an external pillar containing a vertical shaft, at the upper end of which small bevel-gearing was used, giving motion to the vertical shaft, whose bottom end carried a pinion gearing into a sector attached to the fore axle. The motion of the crank-shafts was communicated to the separate axles of the driving-wheels by spur-gearing with two speeds.