at a distance is intrinsically quite as credible as action in contact, and there is no reason, apart from scientific experience, to regard the one as in any respect less probable than the other." It is, of course, a popular idea that no action can take place between bodies except through some connecting link; but there are good grounds for supposing that no two particles of the universe are in absolute contact. If this fact could be thoroughly established, we should be forced to conclude that "action at a distance" is really the law of nature. This point will be referred to by and by. Dr. Croll's views as to the cause of gravitation may be summed up in his own words: "Gravity in all probability is of the nature of an impact or pressure. Some of our most eminent physicists state that the force of gravity must either result from impact of ultramundane corpuscles, in some respects analogous to that of the particles of a gas (which has been found to be capable of accounting for gaseous pressure), or it must result from difference of pressure in a substance continuously filling space, except where matter displaces it. That gravity is a force of the nature of pressure is, I think, beyond doubt; but that this pressure results from the impact of corpuscles, or from difference of pressure in a substance filling space, is purely hypothetical. Why not assume it to be a force, without calling in the aid of corpuscles or a medium filling space?" This statement is evidently very vague, and brings us no nearer to a solution of the problem. To assume the existence of "a force" without explaining why or how the force acts seems quite as "purely hypothetical" as the impact of corpuscles or the action of a pressure-medium. In the year 1869, a "New Theory of Gravitation" was presented to the French Academy of Sciences by M. P. Leray. Assuming the existence of a "perfectly elastic" fluid — the ether of space M. Leray supposes "that there exist at every point equal currents crossing each other in all directions," and that two bodies placed in the ether shield each other from the action of these currents, as in the case of the flying corpuscles of Le Sage. The publication of Leray's views elicited from M. Lecoq de Boisbaudran a "Note on the Theory of Weight" read before the French Academy on September 20, 1869. On some points he agrees with M. Leray; but on others his ideas are different. He says: "I admit that two bodies separated by an absolute void can not act on each other; that action takes place only by contact, the play of forces following the laws of ordinary mechanics. If there existed but a single kind of atoms, the interchange of forces occurring between equal masses, two atoms could not unite. Force and matter would exist, but not attraction. There are, then, at least two kinds of primordial atoms of different masses. The smaller may be called æther; the others, ponderable atoms," and "it is to the longitudinal vibrations of the æther that I attribute the cause of weight." In 1870, Professor Guthrie - apparently in ignorance of the earlier researches of Dr. Guyot-made some experiments with a tuning-fork, and found that, when vibrating, it exerted an attractive influence on light bodies suspended near it. He says: "Though the term 'attraction' may have been occasionally used in the above to denote the tendency of bodies to approach, the line of conclusions here indicated tends to argue that there is no such thing as attraction in the sense of a pulling force, and that two utterly isolated bodies cannot influence one another. If the ætherial vibrations which are supposed to constitute radiant heat resemble the ærial vibrations which constitute sound, the heat which all bodies possess, and which they are supposed to radiate in exchange, will cause all bodies to be urged towards one another." As Taylor points out, "this hypothesis would make gravitation a function of temperature, contrary to all observation," and it is in fact wholly inconsistent with the last three conditions of gravitative action. We next come to the interesting experi ments and views of Dr. Crookes, the eminent physicist. In a paper presented to the Royal Society in 1874, he suggests that the action of his then newly invented "radiometer " might possibly throw some light on the cause of gravitation. This little instrument, which is now familiar to most people, consists of light discs, fixed on arms, and mounted on a point in a hollow glass bulb, from which the air is almost wholly exhausted. One side of the disc is blackened, and it is found that under the influence of radiant heat (or sunlight) the discs rotate. This rotation was at first supposed to be due to the repulsive action of heat; but subsequent investigations proved that this idea was incorrect, the motion being simply due to the difference of heat absorbed by the two sides of the disc and the reaction of the rarefied air remaining in the almost perfect, but still imperfect, vacuum. As lens, Dr. Robison found "that two pieces all experiments have shown that gravita- of glass are not in mathematical contact till tion is perfectly independent of differences they are exerting a mutual pressure of not of temperature in the bodies mutually less than one thousand pounds per square attracted, it does not appear that Dr. inch. For we must not conclude that they Croll's views are well founded, or that are in contact till the black spot appears; there is any relation or analogy between and even then we dare not positively affirm the motion of the radiometer discs and it. My own decided opinion is that the the mystery of gravitative action. glasses not only are not in mathematical contact in the black spot, but that the distance between them is vastly greater than the eighty-nine thousandth part of an inch, the difference of the distances at two successive rings." According to Taylor, the statical theory of gravitation is open to the objection of "the obvious irrationality of a stable nonequilibrium;" and there is no real difference between this pressure hypothesis and the idea of an ether increasing outwards Why the ultimate atoms of bodies should from the centres of material bodies. He attract at a distance and repel when in ably shows that the corpuscular hypothe-close proximity seems a paradox we cansis of gravity is not in any way analogous not understand. The "standing enigma,' to the molecular theory of gases; and that, as Taylor terms it, remains; "and with even if we could consider it as a vera each revolving year new demonstrations of causa, the law of inverse squares would its absolute precision and of its universal not be satisfied in the case of very large domination serve only to fill the mind with masses of matter. He also shows that the added wonder and with added confidence hypothesis of ethereal undulation is "in- in the stability and the supremacy of the capable of inducing anything in the slight-power in which has been found no variest degree analogous to gravitation," and that, even were they capable of doing so, the origin of such undulations would still remain a mystery. Even granting a prime mover, we should still be at a loss to conceive how "the initial impulse is converted into vibration." The great objection to every kinetic theory of gravitation seems to be "its utterly reckless violation of any rational conception of the conservation of energy;" and the authors of these theories seem to think that they "have the Dink of the Infinite on which to draw in every dynamic emergency, without the fear of a depleted treasury, and without any necessity being felt for inquiring too nicely into the balance of the depositor's account." ableness, neither shadow of turning; but which, the same yesterday, to-day, and forever Lives through all life, extends through all extent, Spreads undivided, operates-unspent! J. E. GORE. From The Leisure Hour. A SKATING TRIP IN HOLLAND. FIRST of all, let me at once confess I am not a great skater, and I have no sev enty-mile runs to record, or marvellous stories of how many (or how few) minutes I took over such and such a mile course. Taylor is finally disposed to consider My experiences are all very small, and gravitation as an "ultimate phenomenon," just such as any chance reader of the or, in other words, that it is an inherent Leisure Hour would be likely to have. property of matter. The phenomena of One thing, however, does make the trip I elasticity and the observed resistance of have to tell about notable, and that isall substances to compression seem to it was taken during the marvellous winshow that a force of repulsion exists beter of 1890-91. The abiding, worrying tween the component molecules of matter. "And thus, whether we contemplate the infinitely small or the infinitely grand, in every case comes back upon us the wide induction, that the action of matter in atom, in molecule, or in mass is ever at a distance! Of actual contact there is probably no instance afforded in nature, excepting in the intimate substance of the ultimate atom." In the well-known experiment of Newton, in which a glass plate is placed on the convex surface of a thought when going a-skating of most average mortals - if they are anyhow out of their teens-takes shape in the cautious words: "Is it safe?" In last winter all care could be thrown to the winds. Why, they drove a coach and four on the Thames! It was safe everywhere, and in Holland it was doubly safe. I was fortunate in having pleasant companionship in crossing from Harwich to Rotterdam, and again in returning; but a part of the time in Holland I was abso lutely alone, and in a place where not a | I fairly wished that ice would open and soul spoke English. Till that time I had swallow me up out of the gaze of those always thought what a nice fellow and horrid searching eyes. The mob jeered pleasant companion I was; then I thought I had never met a greater bore, or a man whose mind was such a desert drear. as I scratched along in very lame duck fashion; little boys on big skates tied on with worsted swept in front of me and looked impudently up in my face and "boohed" and "yaahed;" and wherever I went I was followed and mobbed like some poor modest owl by impudent sparrows. This, however, soon came to an end, and when once I could feel my legs I began to grasp what lovely ice I was on, and to appreciate how much harder it was than the ice we have at home. Joy returned, and I managed to free myself of the feeling that I was a sort of doddering old idiot, who ought to be in a bath-chair rather than on skates. But we must forego these moralizings and start on our trip. I have now been four winters to Holland, and each time perversely, in spite of warning, gone the wrong route. The best is by Queenborough and Flushing— less sea, and one is fit the same day of crossing to put on skates and do a mild run. As I have said, we landed at Rotterdam. All the way up the Maas the river was full of great blocks and floes of drifting ice some so large that the steamer thought precaution was best, and eased out of their way; and then, when it thought it was safe, it would go "What bird was that?" I asked myself, smack into the middle of the pack; and as a great shadow swept across my the grinding of the ice against her iron course. A hooded crow, and another, and sides made noise enough in the ears of another; and soon I found out that hoodie those who were still below in their berths is indeed a common bird here - the oppo to cause disagreeable thoughts of holes site, too, in his habits with us; for in being knocked in the ship's sides. We England he is the shyest and most cun. were told, however, the noise was out of ning of birds, difficult to approach even in all proportion to the danger, and we finally those districts he frequents; but here he arrived without mishap. On board we is a sociable bird, living in the towns. had two young Dutch gentlemen, who hopping about on the ice before the were being educated in England, and they skater, and stalking placidly on the frozen were kindness itself in getting our tickets, roadways right under the noses of the settling with porters, and performing all sleigh-horses who race by with jingling those little courtesies that make a journey bells. I went to the Zoological Gardens, pleasant instead of painful. Whenever and though much of it was shut up and wherever I have been in Holland I or under matting, owing to the severe have always found the greatest politeness weather, I saw enough to show it is a and even profuse hospitality from the mid- considerable rival to our own well-kept dle classes; but it ends there. The man gardens. The Zoological Society of Lonof the people may not always mean it, but don have lately had a very large aviary he is nevertheless very rude frequently; built for the herons and gulls on the lines always grumpy, or diffident, or what you of the one here, but this one appears big. will, he can be at times downright insult-ger to me; and I noticed many nests, and ing. Here I do not so much wish to point out the townsman as I do the countryman. I have had now pretty fair experience in my sketchy rambles of very various people, and I certainly should place a lowclass Dutchman very low indeed. We first put on our skates ordinary running skates in the park at Rotterdam. It was rather a ticklish moment that, standing up and starting off before an interested crowd of Dutchmen. I am not a professional, as I have before said, and at no time am I quite as strong on my legs as James Smart or Mr. Charles Tebbutt; but when, in addition to my ordinary small powers, I found I had not recovered from the sea-voyage, and that my legs were very shaky, and my knees showed a loving disposition to knock and rub noses, was told that they rear so many of the common sort of herons and gulls that they let some each year escape; and I myself saw some of these liberated captive-born birds sitting on the top of the aviary, very literally coveting again the flesh-pots of Egypt, for inside the netting was food in plenty and outside there was none. No one ever stays long at Rotterdam; it is the fashion to abuse it and generally run it down. As a matter of fact, there is plenty of interest in it, and it would repay going through quietly. Amsterdam was to be our centre; so we took train and enjoyed the feeling of travelling quickly without having our internal machinery all thrown out of gear, as it had been travelling across that horrid strip of sea. My friends were going to the Amstel Hotel, so I went too. There they made us very comfortable; but I wished several times they would push it a little nearer the centre of the town. Especially I wished it after I had been to dine with a hospitable Dutchman, who lived some way out, and from whose house I returned by train not reaching Amsterdam till one o'clock in the morning; no cab at the station, and I had to walk. I thought I knew a short cut, but found, to my dismay, that the short cut led me clean wrong, and I had to retrace my steps all the way back and start afresh. The midnight cat of Amsterdam sings just like his London brethren, and it made me feel a little more at home as I tramped the otherwise deadly silent streets and at last arrived at the Amstel, where a glimmering light in the hall showed me some one was about, and a sleepy porter at last unbolted the door. But I resolved from that hour I would never again stay at the Amstel unless they moved it nearer the central station. I have often been told that travelling is "so cheap, you know, in Holland;" as a matter of fact, in the big towns it's exactly the same as everywhere else — if anything, a little dearer. Right away in the country you may here and there drop on some quiet old-time inn where they have not learnt all the modern tricks of hotel extortion. But it is no good thinking that a trip to Holland can be done cheaper than a trip to any other part of the Continent. I am speaking now from the ordinary standpoint of a man who is not a Dutch scholar, and, therefore, is compelled to go to only such places where there will be a reasonable chance of his being understood when he uses his mother tongue. I have no doubt, from the experience I have had from my several trips, that, if one could speak Dutch well, one might perhaps travel and live on very little. There were races going on when we arrived there, but we did not go to see them, as hanging about on an exposed stand, freezingly cold yourself, whilst you watch others skate, cannot be said to be the most pleasant occupation. So we (two Englishmen, one my senior and one my junior, and myself) went round to see a gentleman whom I had an introduction to, and he in the kindest manner gave us all sorts of information as to where we should find the best runs, and ended by putting us under the guidance of a young friend of his, who spoke English, and who in next to no time ran home, changed his business clothes for a very workmanlike skating costume, and led us off to the Y, which is just behind the central station. We had decided that we should above everything like to skate on the Zuider Zee, and our excursion was to end at the Isle of Marken; and, had we not had our kindly guide, I don't think we should ever have got there; for, although we had a good map, all the country being covered with snow, it was practically impossible to tell land from water, excepting always where runs were kept swept on the ice. Once or twice we thought we were on land when we were really on ice, so substantial was the feel, and so beaten down was the snow; and even our guide himself, a Dutchman born, was continually having long confabs with the different people we met. This was, I know, very much on our behalf, as he knew the way, but he wanted always to get us the best way and show us the best ice. And well he performed his task. All Dutch skates are tied on either with leather thongs or laces, or with list-string, and the quickness with which they put their skates on is really amazing. I own to hate putting my own skates on, but in Holland you have to; for, though there are men and chairs, not one in a hundred knows how to screw and strap them on properly, and you have to do it yourself. I was the slowest of the three in getting mine on always, and I felt very purple and breathless after it; but, at last, all is ready and we are off. In a very few minutes it was patent that our new friend was an excellent skater, strong and fast, and he must have suffered much at having to go so slowly, when doubtless he was longing to tear away; but he was far too much of a gentleman to show the least sign of this, and reined himself in to suit our modest capacities. Nearly every Dutchman can skate faster than we could, and, when they choose, can go by you with the most ridiculous ease. Still, we found that even they think we are pretty good at keeping up a fair pace for long distances. The first town we had to steer for was Monnickendam, and we had a really glorious run of some ten to twelve miles right into the town; then we were told we must off skates and walk about a quarter of a mile. Knowing my slowness in adjusting my skates, I preferred to keep them on, and walked through the little town on them a very foolish proceeding, as it spoilt my blades and made my instep very sore; but of this more hereafter. Where we joined the ice again there were collected a lot of ice yachts, and, as we had heard so much of these curious craft, we as they can build; but the one absorbing subject of contemplation to us was their wondrous pantaloons. "How is it done?" asked each of the other. "What's inside? What makes them so stiff, and keep stiff even when they walk or run?" I suggested they were starched; another said they must have a whalebone frame under called another halt and made an inspection and drawing. They were not at all like the yachts that may be seen pictured in the American magazines. They were thoroughly Dutch broad, comfortable, regular boats with seats- -cushions even -high sides, and, of course, painted spick and span. (What a country Holland is for paint, to be sure! They paint every-neath. Our Dutch friend could offer no thing-gates, houses, and even trees and such colors, villainous greens and blues, in close juxtaposition with vermilion and lemon yellow.) The American craft are made all lightness and strength, and in no sort of way are they like boats. A cross roughly gives their ground plan. We wanted very much to have a sail, as we found they were on hire; but there was no wind, and it was useless to think of it. From this point we were on the waters of the Zuider Zee, and as we headed straight for the Isle of Marken we felt all exhilaration. The great, wide, open expanse of ice literally running right round one as far as the eye could reach, with the distant hazy isle growing out of the horizon, was simply lovely. We soon, however, had our ecstasy put under check, for we met two men, who turned out to be fellow-countrymen, who reported that it was useless going on, as in about a mile the swept run ended, and the snow had been blown right over everything, and made progress impossible. They were going back, and we had a solemn council. There was the goal within sight, the promised land; how disappointing to have to give up all our cherished plans! and we finally concluded to do the more British thing and face the foe. Reaching the snowed-up point, my friends took their skates off, but I still foolishly would not; and so we in single file tramped over the snow for a mile or more, when, to our joy, further explanation than that they wore many clothes one on top of another; indeed, were in that particular part of their persons simply living clothes-baskets. They on their side seemed to consider we were all awful frights, and laughed most immoderately - worst of all at me. Men giggled, and girls fairly turned their. heads away and screamed. I got quite hot and nervous, and had to get the assurance of one of our party that there was nothing wrong. They rolled about and roared; and at last one old man, who had been rather polite in showing us about, with a kindly grave face looked at me slowly up and down, and his face began to melt into a big grin, and then he too broke out into most annoying mirth. we saw open spaces enough to justify hopes of skating, and very shortly we were all well under way, and ran straight up to the landing-place of Marken. We were told beforehand of the marvels of Marken fashions, but we were quite unprepared for the preposterous costumes we came across at every step. Asked to form any shapes to give grotesqueness, I do not think any Drury Lane costumier could design anything more absurd than the regulation costume of the men of Marken. It's baggy where it might well be fitting close, and tight and squeezing where more ordinary mortals would make it fit easy. If they don't wear high hats and some, as in my sketch, did they wear head coverings of cloth or silk of as high a sort "Whatever can be the matter?" thought I, and my only conclusion was that I must resemble their own peculiar Guy Fawkes, whoever he may be. It was very vexing. as I wanted to sketch some of the girls' costumes, and it was altogether out of the question; for the moment I looked at any one and opened my sketch book, she at once exploded, pointing the finger of scorn at me, and a whole chorus of "yah, ah, hahs!" made me shut my book and beat a retreat into the inn parlor, where we had a capital little lunch - I still with my skates on. The whole place certainly is most picturesque- - quaint, high, red-tiled roofs on black wooden houses of every size and shape- many leaning this way and that, showing their foundations certainly are not founded on a rock. The air seemed full of Boughton's pictures. At every turn we said, "Why, this is just like Boughton;" but we could not recall that we had ever seen him picture the awful garb of the men. By the time we were ready to start home the afternoon was drawing in, and we had a magnificent panorama of changing sunset color right over the Zuider Zee. The snow itself was no longer white, but a warm cosy color, and the patches of clear ice took the golden reflections of the sky above - delicate greys and greens too ran through the ice, and the shadows of the snowdrifts were pure cobalt and pinkish |