Mr Brandreth's carriage was also mounted on friction wheels, but the axles of the travelling wheels in this ran upon the outside of the rim of the friction wheels, and were kept upon the apex thereof, by guides. The carriage No. 1 was a platform, resting on four case-hardened wheels, 30 inches in diameter ; the axles 3 inches in diameter. One of the axles rolled upon the apex of the rim of two friction wheels, 12 inches in diameter, and 3 inches broad on the rim : the other axle rested on the middle upon one friction wheel, similar to the other; this arrangement was for the purpose of causing the four travelling wheels always to preserve their parallelism with the rails. These friction wheels ran upon bearings 2 inches diameter, and 2i inches long. No. 2 was another carnage of similar construction, with a body for the loading.
Mr. Stephenson's carriage consisted of a platform resting on four travelling wheels, 3 feet diameter, case hardened ; the axles, as ehewn in the drawing, passed through the nave, were turned down to 11 inch in diameter, and rested upon bearings of brass, 31 inches in length, working upon ,'springs. Knowing that the friction of rolling is less than that of attrition, Messrs. Brandreth and Winans expected, by disposing a much greater portion of the motion of the working parts into a rolling motion, than in the common carriages they would effect a corresponding reduction in the amount of friction. The experiments given in the following table were made upon a part of the Liverpool Railway, wrought iron rails 24 inches broad on the top, and the experiments were conducted by Mr. Raetnck in the following manner :—The carriages were allowed to run down a descending plane, at the bottom of which the inclination was in a contrary direction, along which the momentum acquired in their descent on the other plane caused them to run until the friction brought them to rest : the difference of level between the two planes, (in the space passed over) with the distance traversed, giving the amount of friction. The Table on the following page will skew the result.
In making these experiments, the rails were swept quite clean, and kept free from any extraneous matter that would have the effect of diminishing friction ; though when worn bright with use, the surfaces will be much smoother than the state in which the rails were when the experiments were made, and therefore we may, perhaps, take them as the average resistance with experi mental carriages. During the time of making the experiments, the wind is stated to have been blowing across the line of the road, sometimes with a velocity equal to three miles per hour, and at other times quite calm : temperature varying from 320 to 350.
On examining these experiments, it will be seen, that the reduction of friction which was anticipated by the adoption of giction wheels, does• not appear to have been realised ; neither does the reduction in the diameter of the axles of Mr. Stephenson's carriage produce that effect which might have been expected.
Messrs. Summers and Ogle had a patent in April, 1830, for a tubular boiler, especially designed for locomotive purposes, which has already been described under our article Borten ; since that period several steam carriages have, we believe, been constructed by the patentees, in which their tubular boiler has been introduced. We have never seen any of these machines, except the frame of one that was constructing at the premises of Mr. Hayne, the engineer, which appeared to us to be very ably designed and executed. Three vibrating cylin ders were placed upon it at the back, which were to work a three-throw crank on the axis of the running wheels ; and as each of these throws were apart, or equidistant in the circle, the conversion of the rectilineal motion into rotatory was effected with great uniformity of force. Messrs. Summer's and Ogle's carriages were, however, seen in action upon many of our public roads by myriads of people, and the reports of their performances, in the newspapers, were generally of a very flattering description ; but sometimes of an opposite character. It was our intention to have inserted some drawings and descrip tions of them, which we have been promised, but their non-arrival at the time we are going to press, obliges UB to omit them. In lieu of them we shall here insert the inventors' own aceonnt of the construction and performance of their carriages, as given in evidence by them before a Committee of the House of Commons in 1831.
"Mr. Nathaniel Ogk examined.—Has (in conjunction with Mr. Summers) combined the greatest heating surface in the least possible space with the strongest mechanical force, so that they work their boiler at 2501bs. pressure of steam on the inch with perfect safety. Their experimental vehicle, weighing about 3 tons, has been propelled from London to Southampton, and on the roads in the vicinity of Melbrook, at various speeds. The greatest velocity obtained over rather a wet road, with patches of gravel upon it, was from 32 to 35 miles an hour, and, on a good road, could have increased that velocity to 40 miles. They have ascended a hill with a soft wet bottom, rising 1 foot in 6, but at rather a slow rate. They have ascended one of the loftiest hills near Southamp ton, at 161, miles an hour. Went from the turnpike-gate at Southampton to the 4-mile stone on the London road, a continued elevation with one very alight descent, at a rate of 24i miles an hour, loaded with people Their present experimental boiler contains 250 superficial feet of heating surface in the space of 3 feet 8 inches high, 3 feet long, and 2 feet 4 inches broad, and weighs about 8 cwt. The two cylinders communicate by their pistons, with a crank-axle, to the ends of which either one or both wheels are affixed, as may be required. One wheel is found sufficient, excepting under very difficult circumstances, and when the elevation is about 1 in 6, to impel the vehicle forward. Explosion is impossible, because the cylinders of which the boiler is composed are so small as to bear a greater pressure than could be produced by the quantity of fire beneath the boiler ; and if any one of these cylinders should be injured, it would become merely a safety-valve to the rest. Have never, even with the greatest pressure, burst, rent, or injured their boilers ; and they have not once required cleaning, after having been twelve months in use. Work usually at a pressure of 247 lbs. on the square inch, but they have worked at a greater pressure than that. Always travel with the safety-valve on the left ; when the fire is only moderately good, the steam is always blowing off, even up the steepest hills. The fuel they use is soft and good coke ; and there is no smoke.
When going at 10 miles an hour, can stop within a less space than a carriage drawn by horses can. Their present carriage has only three wheels ; so that the centre or guiding wheel rolls that portion of the road which has been hitherto cut up by the action of the horses' feet. The front wheel is 41 inches broad in the tire ; the two hind ones about 3 inches broader, that the carriage can draw double its own weight very well. Has seen nineteen persons upon it when going at the rate before mentioned. Thinks the injury done by steam carriages not one-half of that which is caused by horse-drawn carriages. Their wheels are cylindrical, with flat tires, and 5 feet 6 inches in diameter. Have never met with any accident; not one bolt, not one @crew, has ever given way during twelve months, and under circumstances which would have destroyed any other carriage. They have, beyond all question, realized the power of pro pelling vehicles of any weight at any required velocity, and the remaining improvements they are engaged in regard slight details merely. Finds from experience that the larger the cylinder the better.',' Mr. W. AlItoft Summers, engineer, examined.—Has superintended the building of two steam vehicles; the lightest of the two weighed about 2 tons 10 cwt. Travelled in it when there were ten persons upon it, at the average rate of about 9 miles an hour, from Cable-street, Wellclou-square, London, to within two and a half miles of Basingstoke, when the crank shaft broke, and the car riage was put into a barge and sent back to town. This is not the cartage, however, to which the previous evidence of Mr. Ogle refers, nor is it upon the some principle, except that the boiler with which it was fbrnished has been transferred to the vehicle described by Mr. Ogle. When going to Basingstoke, tried to increase the 'peed, but were unable to do it, because the size of the engines would not consume the quantity of steam generated. There were three cylinders, each 4 inchesin diameter, and the stroke of the piston in each was 12 inches; in the carriage described by Mr. Ogle, the cylinders are 7e inches each, the diameter and the stroke of each is 18 inches. Has travelled in this new carriage 15 miles per hour, with nineteen persons on the carnage. . . . . Has no doubt of its being able to carry 3 tons at the rate of 10 miles an hour, exclusive of its own weight ; and, after certain improvements which they have in view are completed, feels assured that much greater weights may be carried at that rate. Has never tested this by experiment, but grounds his opinion on having seen the steam blowing off at both safety valves with tremendous violence when travelling at the rate of upwards of 30 miles per hour. Has continued travelling at the rate of 30 miles an hour 41 miles very frequently, and could have con tinued longer had they not required a fresh supply of water, the tank not being quite large enough. Since the last improvement in the furnace, they have never found any difficulty, when the fire is in good order, in travelling over the worst and most hilly roads. On arriving at the brow of a bill, they throttle or wire-draw the steam, in order to check the velocity of the engines ; and when they find the bill is so steep that the carriage would run faster thin they wish, they attach two drags to the hind wheels, and with the foot they press on one drag, or both, as may be required,and by ;hat means regulate the velocity of the carnage. The drag does not, however, prevent the wheel revolving ; it consists of a kind of iron band, or strap, which goes round a portion of the tire of the wheel, and the power of breaking is multiplied by levers th a very great extent. Were the carriage to go at the rate of 6 miles an hour only, instead of 10, it would be able to carry a much greater weight than 3 tons; cannot how much. Has used water of every description, but has never found the in the least encrusted. Every time, after arriving at a journey's end, they open a cock communicating at the bottom of the boiler, and perhaps it may be they do not give the extraneous matter time enough to rest. Proved the boiler before it was put into the steam carriage at 864 lbs. on the square inch ; it will support 740 lbs. Work usually at a pressure of from 240 to 260, which they find more economical than any other. The surface of iron exposed to the fire and heated air is 245 superficial feet; the weight of the boiler is 8 cwt. 2 qrs. The iron is about one-tenth of an inch thick. Thin boilers last longer in pro portion than thick ones, because the heat panes sooner through into the water, and has not time to act upon the iron. The passengers are placed in front and the middle of the vehicle ; the boiler entirely behind the body of the carriage and the passengers. Has never had any accident from horses being alarmed ; the noise is not so great as that of a vehicle drawn by horses. Considers the mode they have adopted of disposing of the waste steam preferable to that of Mr. Stephenson. Instead of blowing it into the chimney, in order to cause a draft, they have a fan or blower, which is driven by the engines when in opera tion, and this gives intensity of heat in the furnace. The waste steam from the engine goes into a double casing round the furnace ; they admit a small portion underneath the fire-bars of the grate, and allow the remainder to expand itself into the double casing, after which it comes over the to of the fire and escapes in the form of invisible vapour. Finds this better than throwing the steam direct into the chimney to produce a draft; because where this is done, the aperture must be so much diminished that the waste steam is choked in escaping from the engines, and produces a greater loss of power than is required for working the fan. Finds that, when travelling on a paved road, and that of a rough description, they do not consume more than the fourth of the steam they do on a soft gravelly road. The steepest hill they have ever ascended was 1 foot in 6 ; that was the hill at Shirley, for a distance of about 200 yards. Both the wheels were in gear at the time, and there was not the slightest symptom of their slipping. Ascended it at a velocity of nearly 5 miles an hour, with fourteen or fifteen persons on the carriage. Can atop the vehicle within a distance of 12 feet . . . . The engine is calculated at 20-horse power." On the 19th of July, 1830, a patent was issued to Messrs. Rawe and Bosse, of Albany-street, London, for " improvements in steam carriages and in boilers; and'a method of producing draft" The specification of their patent contains a description, with drawings, of a complete locomotive carriage for the common road.