E. J. Marey

“ The species of animal whose coöperation we borrow are numerous, and vary according to latitude and climate. But whether we employ the horse, the ass, the camel, or the reindeer, the same problem is always presented: to get from the animal as much work as possible, sparing him, as far as we can, fatigue and suffering. ”

“ In studying the force of traction of the horse, and the best methods of utilizing it, we encounter all the problems connected with teams and the construction of vehicles. But, on a subject which has engaged the attention of humanity for thousands of years, it seems difficult to find anything new to say.
If in the employment of the horse we consider its speed and the means of increasing it, the subject does not appear less exhausted. ”

“ Compare the slope of two curves of rates, and you will have the reply to all these questions without being obliged to make special experiments on a measured road, watch in hand.
It is not only to the speed of vehicles that the registering apparatus applies; it traces, though with less precision, the rate of progress of men and animals. We slip into our boots a bellows-sole, which is connected by a tube with a portable odograph. Each pace impresses on the style a small movement, as does each turn of the wheel of a carriage ”

“ But with non-suspended vehicles, in order thus to shock the passengers, disjoint the carriage, and abuse the road, force is necessary. It is the horse which must supply this; so that, independently of the useful work which we demand of them, the animal supplies still other work which gives rise to a multitude of shocks, and has only injurious effects. The employment of suspending springs has rendered the double service of suppressing injurious vibrations and of collecting into a useful form all the work which they represent. ”

“ The horseman is trained to distinguish between these different paces, to correct by the education of the horse those which seem to him defective, to fix by habit those which give to his mount more pleasant reactions or a much greater stability. The artist, in attempting to represent the horse, seeks to transfer his attitudes more and more faithfully, to express better and better the force, the suppleness, and the grace of his motions. ”

“ At the moment when the weight falls and the cord is stretched, the balance inclines, stretching the elastic spring, but the mass of one hundred grammes does not yet move; it is only when this spring is stretched that the mass, obedient to the prolonged action of this elastic spring, begins to move and rises, representing a certain amount of work accomplished.
Thus the suppression of shock in traction economizes a certain part of the moving labor; it is then advantageous to give to the traces of a carriage a certain elasticity. ”

“ There are again a great number of questions which we ask daily without being able to solve them. Does such a draught-horse go quicker than such another? Does this trot better to-day than yesterday? By increasing the ration of oats do we increase speed? ”

“ If we record in a comparative manner the work done by the same vehicle harnessed with rigid traces or supplied with elastic tractors, we see (Figs. 3 and 4) that the area of the curve is greater, that is, that there has been more work expended, while rigid traces have been used. In the most favorable cases that I have met with, the economy of work by elastic traction has been twenty-six per cent.
But, it may be objected, the recording dynamometer itself constitutes an elastic intermediary which suppresses the shocks. ”

“ A good suspension also saves the carriage by suppressing the shocks which put it out of order and destroy it in a short time. Finally, suspension saves the wheel itself. On this subject let me recall a remarkable experiment of General Morin. On a high-road, in good condition, he drove a diligence with four horses at the trot, and laden with ballast instead of passengers. The springs of the vehicle were raised so that the body rested on the axles. After the diligence had passed and repassed a certain number of times, it was found that the road on which it was running was notably deteriorated. ”

“ Our present springs diminish the force of jolts, transform a sudden shock into a long vibration; but the perfect spring ought always to maintain a constant elastic force, to allow wheels and axles all the vibrations which the ground demands of them, without allowing any of these shocks to reach the carriage itself. ”

“ If we wish to express that a train is on a certain point of the line at a certain hour, we shall point out its position on the table, opposite the station or any point of the line which it occupies, and on the properly chosen division of time. ”

“ In fact, there are few questions which touch more closely the very existence of man than that of animated motors—those docile helps whose power or speed he uses at his pleasure, which enjoy to some extent his intimacy, and accompany him in his labors and his pleasures. ”

“ Everybody knows what a dynamometer is, viz., a spring which, yielding to tractions exerted upon it, is deformed in proportion to the efforts developed. Let us adapt to a spring of this kind a pencil which touches a strip of paper, and let us so arrange things that the movements of the wheel of a carriage shall impress upon the paper a motion of translation. ”

“ The other is formed of a similar spring placed in the very inside of the carriage-trace.
If you wish to be convinced of the advantage of this mode of traction, yoke yourself to a hand-barrow by means of a rigid leather strap, such as you see used in the streets of Paris or London, where too often man is employed to drag burdens. When you have well noted the painful shocks which this mode of traction transmits to the shoulders, place between the strap and the barrow the elastic tractor and repeat the experiment. ”

“ At successive instants the train will occupy points on the table always different; the series of these points will give rise to a line which will be descending and oblique from left to right for trains coming from Paris, while it will be ascending and oblique in the same direction for trains going to Paris. The line which corresponds to each of the trains expresses the hours of departure and arrival, the relative and absolute rates of the trains, the instant of passing each of the stations, and the duration of stoppages. ”

“ Fig. 2.—Tracing of the dynamograph for a vehicle drawn by a horse.
To obviate suffering of men and animals is unfortunately not a motive sufficient to induce everybody to modify the old system of harnessing. To certain minds known as positive, it is necessary to prove that elastic traction has economical advantages, and that a horse thus harnessed is able to draw heavier loads. ”

“ To remain in the conditions of ordinary life, have we not sometimes in the country a choice of two or three roads to go from one place to another? To know which is the shortest we appeal to the watch, as if the least duration of a walk corresponded to the least distance. ”

“ It does not then take into account the real movement of the train, which is accelerated or retarded under Fig. 6—Odograph reduced to one third of its diameter. a great number of influences. The problem which we seek to solve, that of a graphic expression of the real rate of a vehicle, supposes that the carriage itself traces the curve of the roads traversed in function of time. By means of the apparatus which I present to you, and which I call the odograph (Fig. 6) , a wagon or any kind of carriage traces the curve of its movement with all its variations. ”

“ This fact, which results from the experiments you have seen, requires to be rigorously proved by the aid of the graphic method. It is to the genius of Poncelet that we owe the record of work expended by different motors. ”

“ But, by letting the smaller weight fall from a sufficient height, at the moment when this reaches the end of its course, it will stretch the cord which holds it, and will develop what is called a vis viva, capable of raising the weight of one hundred grammes to a certain height ”

“ The course of the style, which corresponds to a kilometre, ought to be experimentally determined for each vehicle, for the perimeter of wheels is not always the same. But it is clear that, if from each kilometre-stone to another we obtain five millimetres, for example, for the course of the style, this length will always be found to be traversed each kilometre by the same vehicle. Our apparatus is then a measurer of distances, and dispenses with the necessity of attending to ”