140 



NATURE 



[June 7, 1900 



in speed, comfort and convenience, in the direction of locomo- 

 tion by rail. 



The author went on to consider at some length the question 

 of the conveyance of goods, and by means of a graphical dia- 

 gram showed that up to forty miles motor vehicles, owing to the 

 terminal charges, might compete with railways. The hygienic 

 question and growing difficulties of traffic in large cities was 

 next touched upon. Next the difficulties of the problem were 

 considered, and it was shown that these difficulties were very 

 great ; and so far from the success of the railway system being an 

 argument in favour of the immediate development of locomotion 

 by road, the conditions of the problem were such as to involve 

 improvement exactly in the opjrasite direction to that in 

 which the railway locomotive has been successfully developed. 



No doubt the progress of invention would enable a greater 

 amount of power from a given weight of motor to be obtained ; 

 but the surface to be moved over, which is the real difficulty of 

 the road locomotive, would remain the chief factor of the problem. 



The first section of the paper was therefore devoted to the 

 mechanical problem of the behaviour of the wheel upon the 

 road, and the progress which has been made in this direction. 



Under this head the whole question of resistance upon the 

 road was treated, and the author made a strong point of the fact 

 that there was very little data available for determining resist- 

 ance upon roads at the high speeds now permissible, and with 

 different kinds of tyres now in use. He gave diagrams of horse- 

 power curves of resistance adapted to English measures from 

 the " Tableaux Numerique et Graphique " of MM. Borame and 

 Julien, and a series of graphical results taken with the Viagraph 

 of Mr. Brown, showing the nature of the shocks to a vehicle by 

 roads of macadam, stone, asphalte and wood. 



The subject of pneumatic tyres was then discussed, and also 

 the question of wheels suitable for heavy traffic, and illustra- 

 tions of a number of improved types of wheels for this purpose, 

 which had been invented during the last year or so, were given. 

 With any existing system in which four wheels are used, it 

 was shown that the problem of road locomotion was difficult 

 because of the concentration of the load upon such a limited 

 area of support. Even for heavy traffic the pneumatic tyre 

 rnight come into use in the future as it extends the area of re- 

 sistence by yielding, so that the surface in contact is much 

 greater than in the case of an iron-rimmed wheel, especially 

 when running over stone sets or hard ground. 



Beyond this, it is quite conceivable that, just as in railways 

 the number of wheels has been largely increased until a modern 

 bogie carriage has commonly twelve wheels supporting it, it 

 may be found economical to support a motor vehicle also upon 

 a much greater number than at present. 



The steering of motor vehicles, which was the subject of the 

 next section of the paper, is evidently a very important part in 

 their design, and it may at once be said that with one or two 

 exceptions the great majority of motor vehicles are steered 

 upon the principle which was invented by Ackermann as long 

 ago as 1818. The essential principle of the Ackermann system 

 consists in replacing the pivoted fore carriage of an ordinary 

 vehicle which has one axle for the two wheels, by two short 

 pivoted axles each carrying one of the steering wheels. The 

 conditions of correct running of the wheels are that when their 

 plane is turned, their normals intersect on a point on the line of 

 the axles of the driving wheels. The paper then went on to 

 describe the various modifications of the Ackermann system. 



The next section of the paper was devoted to a consideration 

 of motive power and its transmission to the wheels, and under 

 this head the particular uses and advantages of oil, steam and 

 electricity were considered ; although these various agencies 

 have at the present moment fairly well recognised spheres of 

 operation this must be by no means regarded as the final con- 

 dition of things, or as giving a limitation to the employment of 

 each of these types of motive power. Thus, although at present 

 oil-engines are used for light motor vehicles and steam for heavy 

 traffic, there are very ingenious steam motor-cars both in this 

 country and abroad, while light oil-engines have been applied in 

 France and also in this country in connection with heavy traffic. 



Oil-engines, or internal-combustion engines, have by a pro- 

 cess of the survival of the fittest been found so far best suited 

 for light motors and pleasure vehicles. The cycle of the gas- 

 engine is really complex, but these motors have been brought to 

 a high state of perfection, so that upon being started they are 

 found to work for long distances without any attention. If 

 really well designed and constructed, and used with a moderate 



NO. 1597, VOL. 62J 



amount of care, they need little repairs or adjustment, while 

 the objection of smell, vibration, and danger from the use of 

 light petroleum spirit with a low flash point, have all been much 

 reduced, while each year sees an increasing number of places ir> 

 town and country where petroleum spirit can be obtained. 

 Still the objections above-mentioned must be admitted to exist, 

 and this, together with the great expense of pleasure vehicles, ha& 

 to a certain extent hitherto prevented their introduction becoming 

 general. Again, an oil-engine, which has little elasticity in 

 regard to an increased demand for power when ascending a hill, 

 requires elaborate gearing for change of speed, which may be 

 after a time, if not at first when the car is new, a very noisy 

 and objectionable feature. Heavy-oil engines for internal com- 

 bustion have been tried for motor vehicles, but the difficulties of 

 starting and smell have not yet been satisfactorily overcome. 



Steam, or external-combustion motors, require not only a 

 generator or boiler, but also a condenser, in addition to the 

 steam-engine itself. The latter is not used with all motors, but 

 in winter the cloud of steam which must be visible in damp 

 cold weather at a little distance from the exhaust, even if the 

 steam is superheated, really contravenes the Act, which states, 

 "No smoke or visible vapour must be emitted, except from any 

 temporary or accidental cause." Steam introduces a more com- 

 plicated array of pipes and fittings, and requires more attention 

 and skill in working, but it is highly probable that such im- 

 provements will be made in connection with steam motors, that 

 no skilled attendant will be necessary. There is already at least 

 one steam system which is entirely automatic, whilst others are 

 to a great extent so. It is not too early to speak as to the prac- 

 tical and commercial success of any of the systems using steam, 

 but if a condensing steam-engine, automatic in action, with a 

 boiler which is perfectly safe from any fear of explosion, car^ 

 be produced, it may safely be predicted that there is a great 

 future before it, both for light and heavy traffic, as it would 

 have the advantages of great power and elasticity, freedomi 

 from smell, and if using heavy oil, or even coal or coke, would 

 be free from the danger and trouble incidental on the employ- 

 ment of light oil, especially abroad. Moreover, the ease with 

 which a steam motor can be started and stopped, and more 

 particularly reversed, cannot be over-estimated. 



Fuels, other than coal, coke or oil, have been the matter of 

 careful consideration by motor-car designers. The most promis- 

 ing of these is acetylene, which, as derived from calcium carbide, 

 enables a much greater quantity of energy to be obtained from 

 a given weight of fuel ; but although it only requires one-fourth 

 of the weight of calcium carbide to produce a given amount of 

 work as compared with coke, the expense at present makes its 

 use commercially impossible. 



Electrical motors are clean, extremely convenient and simple, 

 free from all vibration and danger and altogether an ideal type 

 of motor. The limitations in the use of electricity are, however, 

 very serious, and are discussed later in the paper. 



The details of internal combustion motors are discussed under 

 the six headings upon which their success more or less depends, 

 viz. : (i) carburisation, (2) ignition, (3) starting, (4) govern- 

 ing, (5) balancing, and (6) cooling. 



The subject of steam is then treated at considerable length, 

 and types of the more important steam heavy motor vehicles, 

 such as those of Thorneycroft, Simpson and Hodman, Musker, 

 Coulthard, Bayley and Clarkson and Capel are given, together 

 with various examples of water-tube and flash boilers, which 

 may be said to be the two types of boilers specially suitably for 

 motor vehicles on account of their high steaming capacity in 

 proportion to their small weight. 



In considering the actual results which have been obtained by 

 motor vehicles, a distinction is made between pleasure vehicles 

 and those for the conveyance of goods. For the former, the 

 actual cost of working is not by any means the first consideration ; 

 in a large number of cases, in fact, the cost is comparatively of 

 small importance. Questions of comfort, durability and safety, 

 as well as freedom from liability to break down, are the chief 

 points to be considered. These matters can scarcely be summed 

 up except as the result of lengthy experience, and now un- 

 doubtedly that experience is gradually being acquired. 



When we come to the question of goods traffic, the matter is 

 of course entirely one of cost, including not merely the outlay, 

 working and upkeep, but deterioration, which in road vehicles 

 is exceptionally heavy. Extended trials of actual working are 

 necessary for any final opinion of the relative merits of different 

 types of heavy motor vehicles, and the author has fortunately 



