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CHAPTER XII.

THE CAUSE OF TIDES.

IT has been shown that the doctrine of the earth's rotundity is simply a plausible theory, having no practical foundation; all ideas, therefore, of "centre of attraction of gravitation," "mutual mass attraction of earth and moon," &c. &c., as taught in the Newtonian hypothesis must be given up, and the cause of tides in the ocean sought in some other direction. Before commencing such an inquiry, however, it will be useful to point out a few of the difficulties which render the theory contradictory, and therefore false and worthless.

1st. The intensity of attraction of bodies on each other is affirmed to be proportional to bulk.

2nd. The earth is affirmed to be much larger than the moon ("The mass of the moon according to Lindenau is 1/87 of the mass of the earth" 1), and therefore to have much the greatest attractive power. How then is it possible for the moon with only one eighty-seventh part of the attractive power of the earth, to lift up the waters of the ocean and draw them towards herself? In other words, how can the lesser power overcome the greater?

3rd. It is affirmed that the intensity of attraction increases with proximity, and vice versâ.

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How, then, when the waters are drawn up by the moon from their bed, and away from the earth's attraction,--which at that greater distance from the centre is considerably diminished, while that of the moon is proportionately increased--is it possible that all the waters acted on should be prevented leaving the earth and flying away to the moon?

If the moon has power of attraction sufficient to lift the waters of the earth at all, even a single inch from their deepest receptacles, where the earth's attraction is much the greater, there is nothing in the theory of attraction of gravitation to prevent her taking to herself all the waters which come within her influence. Let the smaller body once overcome the power of the larger, and the power of the smaller becomes greater than when it first operated, because the matter acted on is nearer to it. Proximity is greater, and therefore power is greater.

4th. The maximum power of the moon is affirmed to operate when on the meridian of any place.

How then can the waters of the ocean immediately underneath the moon flow towards the shores, and so cause a flood tide? Water flows, it is said, through the law of gravity, or attraction of the earth's centre; is it possible then for the moon, having once overcome the power of the earth, to ] et go her hold upon the waters, through the influence of a power which she has conquered, and which therefore, is less than her own? Again, if the moon really draws the waters of the ocean towards herself, can she take them to her own meridian, and there increase their altitude without depressing or lowering the

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level of the waters in the places beyond the reach of her influence? Let the following experiments be tried, and then the answer given:--

1st. Spread out on a table a sheet of paper of any size, to represent a body of water; place an object or mark at each edge of the paper, to represent the shores. Now draw the paper gently upwards in the centre, and notice the effect upon the objects or marks, and the edge of the paper.

2nd. Take a basin of water, and carefully note the level round the edge. Now place the bottom of a small lift-pump upon the surface of the water in the centre of the basin. On making the first stroke of the pump, the water will be slightly elevated in the centre, but it will recede or fall in at the sides.

In both the above experiments it will be seen that the water will be drawn away from the sides representing the shores when it is elevated in the centre. Hence the supposed attraction of the moon upon the waters of the earth could not possibly cause a flood-tide on the shores which are nearest her meridian action, but the very contrary; the waters would recede from the land to supply the pyramid of water formed immediately underneath the moon, and of necessity produce an ebb tide instead of the flood, which the Newtonian theory affirms to be the result.

The above and other difficulties which exist in connection with the explanation of the tides afforded by the Newtonian system, have led many, including Sir Isaac Newton himself, to admit that such explanation is the least satisfactory portion of the "theory of gravitation."

From this point we may proceed to enquire: "What is

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the real cause of the tides? The process must be purely Zetetic--first to define the leading term, or terms employed; secondly, to collect all the facts we can which bear upon the subject; and thirdly, to arrange the evidence, and see what conclusion necessarily appears.

The tide is either the rising and falling of the water in relation to the land; or the rising and falling of the land in relation to the water; but as it is not at this stage decided which is the case, the following must be the definition of the word tide:

DEFINITION.--Tide is the relative change of level between land and water.

FACT 1.--There is a constant but variable pressure of the atmosphere upon the surface of the earth and all the waters of the seas and lakes which lie upon and within it, and upon all the oceans which surround it.

PROOF.--The workings of an air-pump, and the readings of the barometer wherever experiments have been made. During storms at sea it has been found that the commotion is almost confined to the surface, and seldom extends to a hundred feet below: at which depth the water is always calm, except in the path of currents and local submarine peculiarities.

The following quotations, gathered from casual reading, fully corroborate the above statements:

"It is amazing how superficial is the most terrible tempest; divers assure us that in the greatest storms calm water is found at the depth of 90 feet. 1

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"This motion of the surface of the sea is not perceptible to a great depth. In the strongest gale it is supposed not to extend beyond 72 feet below the surface; and at the depth of 90 feet, the sea is perfectly still." 1

FACT 2. Water is (except to a very small degree), incompressible.

PROOF. Globes of metal--of gold and silver, of lead and of iron, the last a large bomb-shell, have been filled with water, and subjected to the force of powerful hydraulic machinery, and in every instance it was found impossible to make them receive any appreciable addition. In some

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instances, when the hydraulic pressure became very great, the water, instead of exhibiting any signs of compression, was observed to ooze through the pores of the metal, and to appear on the outer surface like a fine dew or perspiration.

FACT 3. The atmospheric air is very elastic and greatly compressible.

PROOF. The condensation of air in the chamber of an air-gun; and numerous experiments with an air-pump, condensing syringe, and similar apparatus.

FACT 4. If a raft, a buoy, a ship, or any other structure which floats on the open sea, is carefully observed, it will be seen to have a gentle and regular fluctuating motion.

PROOF. However calm the water and the atmosphere, this gradual and alternate rising and falling of the floating mass will generally be visible to the naked eye. But a telescope (which magnifies motion as well as bulk) will show its existence invariably.

FACT 4. Floating masses of different sizes and densities, being in the same waters, and acted upon by the .same influences, fluctuate with different velocities.

PROOF. Observation with the naked eye and with the telescope.

FACT 6. The largest and heaviest floating masses fluctuate less rapidly than the smallest and lightest.

PROOF. Observation as above. A very striking illustration of the facts 4, 5, and 6, was observed by the author and many friends in Plymouth Bay, in the autumn of 1864. He had previously .delivered a course of lectures

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in the hall of the Athenæum in that town; during which these and other phenomena had been referred to. At the same period the triennial yacht race was advertised, and as many as chose to do so were invited to meet him on the rocks near the bay, early on the morning of the race. There had assembled almost every form and size of vessel, from the smallest yacht to the largest, as well as merchant and war ships. Among the latter was observed laying alongside and within the great Breakwater, the large iron-clad ship, the Warrior. The various phenomena were observed by the whole party of ladies and gentlemen, not one of whom expressed a doubt as to their reality.

The Warrior, being farthest away, and very large and heavy, was an object of more special scrutiny. With telescopes her long black hull was seen against the grey stone of the breakwater, to slowly fluctuate, and almost with the regularity of a pendulum.

FACT 7. Wherever the general pressure of the atmosphere is greatest or least, so are tides in the ocean less or greater than usual.

PROOF. The records of self-registering barometers in use in various parts of the world.

FACT 8. The velocity of a flood-tide increases as it approaches land.

PROOF. Actual experiment. It is also a fact well known to sailors engaged in coasting service.

FACT 9. If we go out in a boat with an ebb tide, we find the velocity decreasing as we leave the shores and channels, until we reach a certain point where the water is found to merely rise and fall but not to progress.

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PROOF. Actual experiment, often tried by, and well known to, pilots and masters of tug steamers.

"The tide never ebbs and flows beyond 40 miles from land." 1

"When a ship is well out at sea, she is not affected by the tide, as it creates no stream in the open sea, the tidal wave sweeping along, but causing no more current than an ordinary billow." 3

It is recorded, that an ancient philosopher in a small boat allowed himself to be carried to sea by an ebb tide, hoping thereby to discover the source of the tides. After drifting many miles, the boat came to a state of rest; and after a short time he found himself being carried back to the shore. He had only been taken out by the ebb, and brought again to land by the flood. He had discovered nothing, and seeing no hope of doing so by repetitions of such a voyage, he destroyed himself by jumping into the sea.

FACT 10. The times of ebb and flood tide at any given part are not regularly exact, often being from half-an-hour to one hour or more before and after the "Port Establishment time."

The times of ebb and flood and the altitude of the tides all over the known world are very various and irregular. Sometimes running up at one end of a river and down at the other, as in the river Thames. Sometimes the flood

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tide returning shortly after the usual and expected tide, as in Southampton waters, the St. Lawrence, the Amazon,, and other rivers.

PROOF. The hydrographic records of various governments--notably the English and American.

"At Holyhaven, near the mouth of the Thames, the tide is actually falling and running down rapidly, when at the same moment it is running up rapidly at London Bridge, and still rising. The first steamer that ever hoisted a pennant under. the Admiralty, namely the Echo, was commissioned under Lieutenant, now Admiral, Frederick Bullock, to survey the river Thames and prove the above fact. Captain George Peacock, second in command, was stationed in one of the ship's boats from 8 o'clock to 3 o'clock, both night and day, on the day before the full moon up to the day after, from June to September, and the same of the new moon of October, 1828, with a tide pole; another assistant being stationed at the same time in the entrance of Holyhaven, with a tide pole; and each having a pocket chronometer to note the exact times of high-water and rise of the tide from low-water mark. The result was that it was found the tide had fallen at Holyhaven six feet, and was running rapidly down while at the same moment it was, at London Bridge still rising and running rapidly up."

"There are four high waters and three low waters in the river St. Lawrence (North America) at the same time; and in the river Amazon (South America) there are no less than six high-waters and five low-waters, at the same time; and in the dry season as many as seven high-waters and six low-waters at the same time have been known." 1

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On many occasions a third tide has flooded the Thames in 24 hours; and some of these extra tides have been higher than the normal tides.

At Southampton there is always a second flood tide two hours after the first.

"The first high water is caused by the eastern current up the Solent and the inset from the English Channel, through St. Helen's and Spithead, meeting near the Brambles. There is a second tide two hours after the first, caused mainly by the stream setting to the westward through the Solent at a rapid rate, assisted by the first quarter's ebb from Chichester, Langston, and Portsmouth harbours, until it meets with a check in the Narrows of Hurst, causing the second rise at Lymington Leap, Southampton, &c. Low water is about 3 hours and 20 minutes after the second high water." 1

"The tidal water-mark at Portishead (mouth of the Avon), on the 16th of August, 1871, at 7 o'clock in the morning, will be about 50 feet higher relatively, than the tidal mark at London Bridge. At Cape Virgin (the eastern entrance of the Straits of Magellan), at half-past eight the same morning, the tidal mark will be about 51 feet higher than at York Roads, (English Reach) towards the Western end of the Straits. At 2 o'clock of the same afternoon the tidal mark at Panama will be about 21 feet higher than at Colon, on the opposite side of the Isthmus; at Noel Bay, in the Bay of Fundy (North America), at 1 o'clock of the same day, the tidal mark will be about 53 feet higher than at Picton, on the opposite side of the Nova Scotian Isthmus, in the Gulf of St. Lawrence. At 5 o'clock the same evening, at Boisee Island, in the Corea, the tidal mark will be about 49 feet higher than at Hong Kong, and about 42 feet

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higher than at Cumsingmoon, at the mouth of the Canton river.

"At Christchurch, and at Granville, nearly opposite and across the channel at 7 o'clock on the same morning, the water-mark will be 34 feet higher at the latter part than at the former. At Piel Harbour (Lancashire), at half-past 11 o'clock in the morning of the same date, the water-mark will stand about 40 feet higher than at the same moment at Rathwollen, Lough Swilly, on the N.E. coast of Ireland, nearly opposite. The tide water-mark at Hull at half-past 6 a.m. or a little later p.m. will be about 28 feet higher than at Berwick-on-Tweed, at the same moment (16th or 31st), and about 32 feet higher than at Margate. At Ballycastle Bay, N.E. coast of Ireland, the tide at the highest springs never exceeds 3 feet, whilst at Piel Harbour and Southerness it rises 28 feet, and at Liverpool 26 feet, independent of forced tides by the wind. At Poole it never exceeds 7 feet; whilst at Hastings it rises 24 feet, at Tenby 27 feet, and at Wexford, opposite, only 5 feet; at Ark-low 4 feet, and Waterford 13 feet." 1

HEIGHT OF TIDES IN VARIOUS PARTS OF GREAT BRITAIN AND IRELAND.

In these extracts abundant proof is given of the irregular character of the tides, both in respect to times and altitudes.

FACT 11. Every ship, raft, or other floating mass, in addition to its visible fluctuation, has a tremulous motion or tremor of the whole body.

PROOF. On the deck of any vessel or other floating body let the most delicate instruments be placed, such as spirit-levels, poised compasses, &c., and the tremulous motion will easily be recognised.

FACT 12. The earth has a tremulous motion more or less at all times.

PROOF. If a delicate spirit-level be firmly fixed on a rock or on the most solid foundation it is possible to construct, and far away from the influence of any railway, or blasting or mining operations, the curious phenomenon will be observed of continual but irregular change in the position of the air bubble. However carefully the level may be adjusted, and the instrument protected from the atmosphere, the "bubble" will not maintain its position long together. A similar effect is noticed in the most

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favourably situated astronomical observatories, where instruments of the very best construction, and placed in the most approved positions, cannot always be relied upon. without occasional and systematic readjustment.

The following quotation affords a good illustration of the tremour above described:---

"MARCH 12TH, 1822, in Adventure Bay, Island of South Georgia, we anchored in seven fathoms water, latitude 54° 2´ 48″ S., longitude 38° 8´ 4″ W. The head of this Bay being surrounded with mountains, I ascended the top of one of them for the purpose of taking the altitude of the sun when at some distance from the meridian; but after planting my artificial horizon, I was surprised to find that although there was not a breath of wind, and everything around perfectly still, yet the mercury had so tremulous a motion that I could not get an observation." 1

FACT 13. Tides in the extreme south are very small, and in some parts are scarcely perceptible.

PROOF. "The rise and fall of tide in Christmas Harbour, latitude 48° 41´ S, longitude 69° 3´ 35″ E., is remarkably small; not on any occasion amounting to more than 30 inches and the usual spring tides are generally less than two feet. The neap tide varies from four to twelve inches, and the diurnal inequality is, comparatively, very considerable." 2

"Auckland Islands, latitude 50° 32´ 30″ S., longitude 166° 12´ 34″ E., high water at full and change of moon took place, at 12 o'clock, and the highest spring tides scarcely exceeded

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three feet. A remarkable oscillation of the tide when near the time of high-water was observed; after rising to nearly its highest, the tide would fall two or three inches, and then rise again between three and four inches, so as to exceed its former height rather more than an inch. This irregular movement generally occupied rather more than an hour, of which the fall continued about 20 minutes, and the rise again upwards of 50 minutes of the interval."

"The same was observed at Campbell Island, South Harbour, latitude 52° 33´ 26″ S., longitude 169° 8´ 41″ E." 1

Along the whole length of southern land discovered by Lieut. Wilkes, near the antarctic circle, and which extended upwards of 1500 miles, very little tide was discovered.

"During the whole of our stay along the icy coast we found no perceptible current by the reckoning and current log. Tides on such an extent of coast there undoubtedly must be, but of little strength, or we should have perceived them. In many of the icy bays we were stationary for a sufficient time to perceive them if they had been of any magnitude, and where the current was repeatedly tried." 2

FACT 14. The tide generally turns a little earlier below than it does above.

PROOF. Colonel Pasley, when operating on the "Royal George," the war-ship which sunk at Spithead, was the first 'who observed and recorded this peculiarity, which has also

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been noticed during diving operations in Liverpool Bay and other places. 1

FACT 15.--Many large inland seas or lakes are entirely without tide, while several wells of only a few feet in diameter have a considerable rise and fall in the water corresponding in times to the tide in a distant tidal sea.

PROOF---Many cases may be found in works on geography and geology.

FACT 16.--If, at any hour of the night, a telescope is firmly fixed, securely lashed to any solid object, and turned to the pole-star, it will be found on continuing the observation for some hours that the star "Polaris" does not maintain its position, but seems to slowly rise and fall in the field of view of the telescope. The line-of-sight will be sometimes above it; in about twelve hours it will be below it; and in another twelve hours it will again be above the star.

This peculiar motion of either the star or the earth is represented by the following diagrams

In fig. 67, the line of sight, T, L, is represented as above the

FIG. 67.

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FIG. 68.

pole-star, P; and in fig. 68, the same line is below it. That such a peculiar phenomenon exists may be proved by actual experiment on any clear night in winter, when it is dark sufficiently long to observe for twelve hours together.

Many more facts could be added to the foregoing collection, but already the number is sufficient to enable us to form a definite conclusion as to what is the real cause of the tides.

The facts 1 to 7 fully enable us to establish syllogistically the groundwork of the reply. All bodies floating in an incompressible medium, and exposed to atmospheric pressure, fluctuate, or rise and fall in that medium.

The earth is a vast irregular structure, stretched out upon and standing or floating in the incompressible waters of the "great deep."

Ergo--The earth has, of necessity, a motion of fluctuation.

Hence, when by the pressure of the atmosphere, the earth is depressed or forced slowly down into the "great deep," the waters immediately close in upon the receding bays and headlands, and produce the flood tide; and

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when, by reaction, the earth slowly ascends, the waters recede, and the result is the ebb tide.

Facts 8, 9, 11, 12, and 16, show results that must necessarily follow this fluctuation of the earth. The velocity of the flood is greatest as it approaches land. If the waters were put in motion by the moon, the velocity would be greatest where the altitude was greatest or nearest the moon, and least the farthest from it or nearest the shores. The reverse is the case in nature.

The line of sight being at a given time above the pole-star, as shown in fact 16 (fig. 67), and in twelve hours afterwards below it, as shown in fig. 68, is exactly the result which must follow a slowly rising and falling earth.

Facts 11 and 12 are also consistent with and necessarily attach to a slowly fluctuating elastic mass like the earth.

In fact 10 we see the irregularity of time in flood and ebb, which arises from the irregular form of the bed of the waters. The submarine channels, banks, and depressions which exist in all directions, the action and reaction, mounting and "back-lashing" of the waters, produce the irregular times and altitudes of the tides observed and recorded in the hydrographic offices of different nations.

In fact 13 we see that out of the reach of the great bulk of the fluctuating earth the waters are but little disturbed; but if the waters were lifted up by the moon they would flow towards and flood the southern or antarctic lands as readily and to as great an extent as the land in the equatorial and northern regions.

In fact 14 we have a phenomenon which could not possibly exist if the tides arise from the action of the moon

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upon the water; for as the action would first be on the surface, that surface would be the first to show change of motion, and the bottom the last.

In fact 15 we see what could not be possible if the moon were the cause of tidal action by lifting the waters underneath her from their normal position. If the moon's attraction operates in one place, what can possibly prevent its action in all other places when and where the relative positions are the same? No direct explanatory answer has yet been given. If, however, the great inland lakes and seas are simply indentations in and upon the land, the water contained in them of course rises and falls with the earth on which they lie; there is no change in the relative level of land and water, and therefore no tide. Just as the fluctuations of a ship would show rising and falling, or ebb and flood tide outside the hull, any vessel on the deck, filled with water, would rise or fall with the ship, and would therefore exhibit no change of level--no tide.

Thus we have been carried forward by the sheer force of evidence to the conclusion that the tides of the sea do not arise from the attraction of the moon, but simply from the rising and falling of the floating earth in the waters of the "great deep." That calmness which is found to exist at the bottom of the great seas could not be possible if the waters were alternately raised by the moon and pulled down by the earth. The rising and falling motion would produce such an agitation or "churning" of the water that the "perfect repose," the growth of delicate organic structures, and the accumulation of flocculent matter called "ooze," which has been so generally found when

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taking soundings for deep-sea cables, could not exist. All would be in a state of confusion, turbidity, and mechanical admixture.

The question: What has the moon to do with the tides? need not entirely be set aside. It is possible that in some at present unknown way this luminary may influence the atmosphere, increasing or diminishing its barometric pressure, and indirectly the rise and fall of the earth in the water; but of this there is not yet sufficient evidence, and therefore the answer remains for the future.

Footnotes

158:1 "Physical Description of the Heavens," p. 352. By Humboldt.

161:1 "Chambers' Journal," No. 100, p. 379.

162:1 "Penny Cyclopœdia," Art. "Sea."

162:2 "London Saturday Journal," p. 71, for August 8th, 1840:

162:3 "Physical Geography of the Sea," p. 265. By Lieut. Maury, U.S.

165:1 "Million of Facts," p. 271. By Sir Richard Phillips.

165:2 Ibid.

165:3 "Treatise on Navigation," p. 11.

166:1 "Is the World Flat or Round?" A pamphlet, by Captain George Peacock, F.R.G.S. Second Edition. Published by Bellows, Gloucester, 1871.

167:1 "Gutch's Southampton Almanack and Tide Tables." Standing note.

168:1 Captain George Peacock, F.R.G.S., in a Pamphlet referred to at p. 166.

169:1 "Liverpool Almanack."

170:1 "Voyage towards the South Pole," p. 52. By Captain James Weddell, F.R.S.E. 2nd Edition, 1827. London: Longman, Rees & Co.

170:2 "South Sea Voyages." By Capt. Sir Jas. Clarke Ross. Vol. i., p. 96.

171:1 "South Sea Voyages." By Capt. Sir Jas. Clarke Ross. Vol. i., p. 153.

171:2 Appendix to "Narrative of the United States' Exploring Expedition," p. 366. By Lieut. Charles Wilkes, U.S.N.

172:1 In "Household Words" for October 18th, 1856, the subject is referred to.