and July which might apply to the object seen by De Vico, assuming it to have been an intra-Mercurial planet. Leverrier did not attempt to discuss these observations, confining his attention to those made about the equinoxes, clearly belonging to a different body.

GEOGRAPHICAL NOTES

SOME of our contemporaries have been a little premature in appointing the Earl of Northbrook to the presidency of the Royal Geographical Society, for at the time when the announcement was first made his lordship was not even a fellow of the Society. The fact, we believe, is that Lord Northbrook has expressed his willingness to accept his nomination by the Council, but there is no likelihood of any election taking place till the anniversary meeting on May 26th.

AT the meeting of the Geographical Society on Monday evening Dr. James Stewart, of the Livingstonia Mission, East Africa, read a paper on the " Second Circumnavigation of Lake Nyassa." The voyage was undertaken in the little steamer Ilala in the latter part of 1877. It was found that Lake Nyassa has hitherto been laid down on our maps too far to the east, and that its position ought to be shifted at the north end as much as thirty miles to the westward. Dr. James Stewart was also fortunate in discovering two harbours such as were needed for the safe navigation of the lake; the one Rombashi inlet or river on the northern coast, and the other the Kambwe lagoon a little to the south of it on the west coast. Mr. James Stevenson afterwards gave a few particulars respecting the explorations now being carried on by Dr. Laws and Mr. James Stewart, of the Bengal Civil Service, in the country on the western side of Lake Nyassa.

THE Abbé Debaize, the leader of the French expedition to Central Africa, sends to M. Richard Cortambert a letter, rejoicing at the success of his expedition so far. He writes from Taboro, in Unyamwezi, and states that

hitherto he has been completely successful; there have

been no desertions, little expenditure, and no misfortunes of any kind. This good fortune he ascribes to his own excellent health, to his firm discipline, and his personal superintendence of all arrangements. He has a very poor opinion of Miramboa, and thinks the English are striving hard to become masters in Central Africa; indeed he hints that "annexation" is not far off. At Mpwapwa, where the sole white population are an English "reverend, a mason, and a carpenter," there are already four stone houses, while there are English stations in Ukerewe, Uganda, and at Ujiji.

THE Daily News Lisbon correspondent states that the Portuguese Minister of Marine has informed the Cortes that he has received a telegram stating that the Portuguese African explorer Pinto, who was separated from his companions at Bihe, has succeeded in traversing Africa from west to east, having reached the Transvaal.

FRANCE and the United States will soon establish a comparison of the longitude of Paris and Washington by cable. As is known, these operations lead to a determination of the velocity of propagation of electric waves. Commander Perrier and M. Loewy have recently published a volume giving the details of the comparison between Paris, Marseilles, and Algiers.

MR. STANFORD has just published a very fine stereographical map of Zululand, with portions of the adjoining territories. On the bases of what observations there are as to the physical conformation of the country, together with the pretty fair notions we have of the courses of the rivers, a good general notion is conveyed of the character of the surface and its various levels. The map conveys, moreover, a great amount of information in a clear and striking manner, that will be extremely useful to those

who wish to understand the history and bearings of the Zulu difficulty.

UNDER the title of "Le Maroc" the current number of the Tour du Monde contains the commencement of a translation of M. Edmondo de Amicis' account of his experiences in Morocco in 1875. The present instalment deals with Tangier, and is accompanied by several illustrations.

WE understand that Prof. Geikie, of Edinburgh, will probably deliver a lecture on Geographical Evolution before the Royal Geographical Society on Monday, March 24.

THE Emperor of Austria has presented Captain von Oestreicher with the medal for letters and arts (literis et artibus) in recognition of his recent highly interesting geographical work, "Aus fernem Osten und Westen."

DURING last year the following journeys were made by Russian explorers in Central Asia :-Generals Stolyetoff and Razgonoff were accompanied during their mission to Kaboul by several topographers and explorers; M. Oshanin has made explorations in Karategin and Hissar; M. Matséeff in Badakshan and Eastern Afghanistan; M. Grodékoff in Western Afghanistan and Herat; M. Bykoff has explored the Amu darya River from Kobadian to Khiva; M. Yavarsky has traversed for the fourth time the region between Tashkend and Kaboul; M. Mayeff has visited for the second time the hilly track between Karshi, Keliff (on Amu darya), Kobadian, and Hissar; and, finally, the steamer Samarkand has navigated the Amu, from Petro-Alexandrovsk to KhodjaSale.

there has been founded at Nancy a new geographical UNDER the title of Société de Géographie de l'Est, society.

A STUDY IN LOCOMOTION1

IF the interest of a scientific expositor ought to be measured by the importance of the subject, I shall be applauded for my choice. 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 labours and his pleasures. The species of animal whose co-operation 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. This identity of standpoint will much simplify my task, as it will enable me to confine the study of animated motors to a single species; I have chosen the horse as the most interesting type. Even with this restriction the subject is still very vast, as all know who are occupied with the different questions connected therewith. In studying the force of traction of the horse, and the best methods of utilising 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. Since the chariot races, of which Greek and Roman antiquity were passionately fond, to our modern horse-races, men have never ceased to pursue with a lively interest the problem of rapid locomotion. What tests and comparisons have not been made to discover what race has most speed, what other most bottom, Moteurs animés; Expériences de Physiologie graphique." Lecture by Prof. Marey at the Paris meeting of the French Association, August 29 1878.

what crossings, what training give reason to expect still more speed?

Lastly, as to what is called the exterior of the horse, and his varied paces, specialists have for long devoted themselves to this department. 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.

These questions, so complicated, I wish to bring before you by a new method, and I hope to show you that the graphic method makes light of difficulties which seem insurmountable, discerns what escapes the most attentive observation; finally, it expresses clearly to the eyes, and engraves upon the memory the most complicated notions. The graphic method was almost unknown twenty-five years ago; to-day it is wide-spread. Thus, in almost all countries, recourse is had to the employment of graphic curves as the best mode of expression to represent clearly the movement of administrative, industrial and commercial statistics. In all observatories apparatus known as registering or recording, trace on paper the curves of variation of the thermometer, the barometer, rain, wind, and even atmospheric electricity. Physiology utilises still more largely recording apparatus; but I shall only require to show you a very small number of these instruments, those which serve to record forces, rates of speed, or to note the rhythms and the relations of succession of very complicated movements.

1. Of the Force of Traction of the Horse, and the best Means of Utilising it.-When a carriage is badly constructed and badly yoked the traveller is jolted, the road is injured, the horse is fatigued more than is necessary, and is often wounded by parts of the harness. Science and industry have long sought to discover these inconveniences, to find out their causes in order to get rid of them. But it is only in our own time that great progress has been made in this respect. When we complain of being jolted in a humble cab, we ought to go back in thought to the time when people knew nothing of the hanging of carriages. No roughness of the road then escaped the traveller. A Roman emperor mounted on his triumphant chariot was, in the midst of his glory, as ill at ease as the peasant in his cart. Except some improvements, such as the use of softer cushions, things went on thus till the invention of steel springs such as are now employed, for the leather braces of old-fashioned carriages still left much to desire.

Does this mean that the present mode of suspending carriages by four and even eight springs is the final step of progress? Certainly not. 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. The search for this ideal spring has engaged the attention of one of our most eminent engineers. M. Marcel Deprez has found happy solutions to the problem of perfect suspension; he will, doubtless soon apply these in practice.

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. The springs of the carriage were replaced and the same movements were repeated on another part of the road; the marked deterioration was no longer produced. It is thus clearly proved that a good suspension is favourable to a good condition of the roads.

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.

Is this all? Do there not remain, even with the best carriages, other vibrations and other shocks which must be pursued and destroyed in order to render more perfect the conditions of traction? You have all experienced, at the moment of the sudden start of a carriage, and even at each stroke of the whip on a living horse, horizontal shocks which sometimes throw you to the bottom of the carriage. In a less degree, shocks of the same kind are produced at each instant of traction, for the speed of the horse is far from being uniform, and the traces are subjected to alternate tension and slackness. Here are veritable shocks which use up part of the work of the horse in giving only hurtful effects which bruise and contuse the breast of the animal, injuring his muscles, and, in spite of the padding of the collar, sometimes wounding him. To prove the disadvantages of this kind of shocks, some experiments are necessary. I have borrowed one from Poncelet; it is easily made, and any one may repeat it. I attach a weight of 5 kilos to the extremity of a small string; taking hold of the free extremity of this, if I gently raise the weight, you see that the cord resists the weight of 5 kilos and holds it suspended. But if I attempt to raise the same weight more rapidly, I bruise my fingers, the cord breaks, and the weight has not budged. The effort which I have made has been greater than the preceding, since it has exceeded the resistance of the cord; but the duration of this effort has been too short, and the inertia of the weight not being overcome, all my exertion has been expended in injurious work. If, instead of an inextensible cord, I had attached to the weight a cord a little extensible, the sudden effort of elevation which I made would have been transformed into an action more prolonged, and the weight would have been raised without breaking the cord and bruising my fingers. To render the phenomenon more easy of comprehension, I shall make a new experiment under conditions a little different.

You see on a vertical support (Fig. 1) a sort of balancebeam, which bears on one of its arms a weight of 100 grammes, on the other a weight of 10 grammes suspended at the end of a cord one metre long. Between these two unequal weights the beam is maintained by a spring-catch, which prevents it from falling to the side of the heavier weight, but which, on the other hand, permits the beam to incline in the opposite direction, if we bring to bear on the end of the cord an effort greater than the weight of 100 grammes. 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 100 grammes to a certain height; but this elevation will only take place on condition that the application of this force does not give rise to a shock. If the cord which sustains the weight of 100 grammes is inextensible, and if that which bears the weight of 10 grammes is the same, at the moment of the fall of the latter, you will hear a snap; a shock agitates

the whole apparatus, but the weight of 100 grammes is not raised. Now suspend this weight of 100 grammes to an indiarubber cord or an elastic spring, and repeat the experiment. You see each time that the weight falls that the 100-gramme weight is raised to a certain extent. But this elevation is effected under peculiar conditions. At the moment when the weight falls and the cord is stretched, the balance inclines, stretching the elastic spring, but the mass of 100 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,

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

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. While the effort of traction of the horse will communicate to the spring movements more or less extended, the progress of the carriage will

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FIG. 1.-Apparatus to show that a vis viva directly applied to the displacement of a mass is lost in a shock, while the same force transmitted by an elastic medium may perform work.

begins to move and rises, representing a certain amount of work accomplished.

Thus, the suppression of shock in traction, economises a certain part of the moving labour; it is then advantageous to give to the traces of a carriage a certain elasticity. One of the most simple methods consists in interposing between the trace and the carriage an elastic medium. Here are some of these elastic pieces, which I call tractors. One of the patterns has been made by M. Tatin; it is composed of a spring which is compressed by traction and deadens the shock. 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, voke yourself to a hand-barrow by

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FIG. 2.-1racing of the dynamog aph for a vehicle drawn by a horse. 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. After that no doubt is possible; the shoulders are no longer bruised by the shaking of the pavement, and a comfort is experienced which will evidently be experienced in the same degree by a horse placed in conditions of elastic traction.

To obviate suffering to men and animals is unfortunately not a motive sufficient to induce everybody to

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FIG. 3.-Tracing of the dynamograph for a vehicle drawn with an elastic intermediary.

draw out the paper, and from these combined movements will result a curve (Fig. 2), which can be resolved into a series of ordinates or vertical lines in juxtaposition, expressing by their unequal heights the series of efforts resulting from each element of the road traversed. The sum of these elementary efforts, otherwise the surface of paper limited in height by the flexures of the curve, will be the measure of the work expended. 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 favourable cases that I have met with, the economy of work by elastic traction has been 26 per cent.

itself constitutes an elastic intermediary which suppresses But, it may be objected, the recording dynamometer

the shocks. But it is not the ordinary dynamometer which I have used in my experiments, but a special dynamometer which undergoes under the strongest trac tions only an almost insignificant elongation. This elongation, amplified by certain organs and transmitted to a distance by a lever fitted with a pen, is recorded in the form of a wavy curve in conditions referred to above. To sum up, in the employment of animated motors for the drawing of burdens, to find out wherever they produce shocks and vibrations, and to absorb them in elastic springs which restores to useful work a force that seemed only to destroy vehicles, tear up the roads, cause the animals to suffer-such is the direction in which much progress has been realised, and much more may still be realised.

2. Of the Speed of Animated Motors.-I shall per