of the barbarous practice; and has gradually enhanced to the people the price of this basis of power, trade, and commerce. For we find, Mr. Brandling states, before the Committee of the Lords in 1830, that the Walls-end Colliery quarried the virgin coal in 1792, for 7s. 10 d. the Newcastle chaldron of 53 cwt., on a product of 30,000 to 33,000 tons per annum; in 1793, the price was 8s. 54d.; and in 1794, 11s. 24d. The diluting system has raised the price so much, that in 1830, from

17s. to 23s. is paid by the people of London for the same quantity of coal, to say nothing of the inferior quality; and yet the colliers' earnings under this trebled price amount to a smaller sum than at the former periods. After this, Mr. Deakin will not be troubled much longer with doubts of the existence of collieries worked by the diluted ventilation in the state I previously noticed.

In reference to his remark that such a method of quarrying coals would not be permitted even under the sea; I must

state, that much of the best knowledge I possess concerning the diluting system in coal mines, I obtained under the sea, at a considerable distance from the beach, and many fathoms below the bed of the waters; even in that coal field, where, only a few days ago, this murderous system of employing the men in a medium of mixed gas, caused by an explosion, the death of 22 human beings, not for any crime, but for their industry in supplying an article essential to our welfare as a nation.* This was only one more added to the thousands of explosions, fatal to men and horses, which have occurred there and at other places at the bottom of the sea. The statements affords us information of the fortunate victims thus instantly killed in the pit; but they omit any account of those unfortunate sufferers who are conveyed home, to expire after the most intense agonies endured for a day, week, or even more; and which are not added to the fatal list, because they receive Christian rites, die in their beds, and have Christian burial.

a

I regret that Mr. D. should place such great reliance on the present method of diluting, as to assert that " good steady current of atmospheric air is the thing, and that nothing besides will do." In all my acquaintance with coal mining, during almost forty years, I have not been so successful as to find this one thing needful; and I do not expect to be, while I can remember the proverb, uncertain as the wind," and find the barometer indicate changes of density several times in a day, and there must necessarily be a change in the resistance of the air to the hydrogen, as the former may be at 28° or at 31°.

66

as

When Mr. D. has perused the statements to which I have directed his attention, any further explanation he may then require, I cheerfully will supply through your columns. Yours, &c.

Nov. 26, 1831.

J. RYAN, F. S. A. Middleton Hill Mines, Montgomeryshire.

stant

Wigan, by which twenty-eight more persons have perished; making in all, a sacrifice of fifty lives, during a couple of months, to the present dangerous system of mining. This, too, includes those only who have been instantly killed outright; while, as Mr. Ryan truly suggests, there are on all these occasions numbers who survive only to die after a short time of the injuries they received. Does not the con recurrence of such deplorable events as these, constitute a case that calls loudly for Parliamentary inquiry? It is manifest that neither the diluting plan, as Mr. Ryan calls that, by means of atmospheric ventilation, nor yet the Safety Lamp of Sir Humphry Davy, have proved of efficiency enough to prevent a dreadful waste of human life; indeed it appeared from some statements which we laid before our readers, a considerable time back (vol. xii.) that more lives have been lost on an average since the introduction of the Davy than before. We extract from The Times of the 29th instant, a Narrative of the last explosion at the Kitgreen Colliery, communicated to that journal by Mr. Edward Stanley, Land and Mine Surveyor.

"On Thursday evening last one of those explosions of inflammable gas which have of late been so often attended with great sacrifice of human life, took place in the Colliery of Messrs. Woodcock and Haliburton, at Kitgreen. The pit in which the accident occurred, is known by the name of the "New Engine Pit." It is of unusual depth, and from the circumstance of the workings being intersected by several faults or breaks, is particularly favourable to the accumu lation of inflammable gas. The depth of the shaft or pit is 245 yards; from thence a descent by an inclined plane takes the workmen to the coal. The perpendicular to this hypothenuse is 170 yards, making a total depth from the surface to the coal of 1245 feet. The report of the explosion was terrifically lond, and heard in the township of Addington, a distance of eight miles. As regards the immediate cause of the accident, little can be said with certainty. From personal enquiry on the spot, and information kindly afforded by Mr. John Woodcock, it appears that the underlooker of the pit and his assistant were in the colliery, examining it and making some measurements, when both had returned to the bottom of the pit. The information of a person who ascended prior to the explosion, shows that the assistant underviewer and one of the men

Making a total of

8

28

The accident is in nowise attributable to any negligence on the part of the owners, or the deceased underlooker, John Williams, as the circulation of pure air was abundant, had it not been overpowered by an instantaneous rush of inflammable air from the old workings. The deceased underlooker, during the course of a conversation a fortnight ago with the writer of this narrative, declared his confidence in the free ventilation of the works, and the facilities afforded him by his employers, for carrying into effect every means that could be devised for the safety of the workmen. In confirmation of the above fact, it may be stated, that during a period of 40 years, has Mr. Haliburton's attention been directed to the grand de. sideratum of ridding coal mines of this dreadful foe to the collier. Of late the dangers and hardships of this adventurous class of men, have been advocated in a paper that has appeared in that popular work, the Mechanics' Magazine. It Is there shown in the person of Mr. Ryan, that individual exertion, even in the cause of science and humanity, was overthrown by the narrow-minded prejudices and jealousies of a few interested managers at Newcastle-on-Tyne, who had no wish to see their own talents eclipsed, when he solicited a trial to clear the mines of inflammable gas. In the last No. of the work referred to (No. 423) Mr. Ryan's plan is given to the public, and ought to be republished by every paper that has circulation in the mining districts."

EXPERIMENTS ON THE MOTION OF
FLUIDS.

Sir, Trebor Valentine (page 107) regrets that some of your correspondents do not give their opinions upon the “ Mo

Why so-if as afterwards suggested, the accident was caused by "an instantaneous rush of inflammable air from the old workings?"-Er. M. M.

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tion of Fluids." I have not yet had an opportunity of referring to the pages he alluded to upon the subject; but being particularly fond of theorizing-if I may use the word-from which the most useful practical knowledge is often attained --I beg leave to make a few observations, begging T. V. to consider them as written by one individual, who, although possessing great "love of science," is not connected with any branch of mechanics as a business, and cannot, therefore, be expected always to make right inferences or conclusions. My remarks will principally be made with reference to 'I'. V.'s explanatory figures, Nos. 1 and 3, page 108, the plan of which I have in some measure followed.

Having procured a round leaden pot, 34 inches deep, by 34 inches wide, I fixed in the centre of the bottom a piece of inch pipe 24 inches long, one inch being within the pot, and one end with a tin cap and hole in it, about 3-16ths of an' inch diameter. The pot contained, when full, 28 oz., 8 oz. being below the top of the pipe. In my first experiment, with the tin cap upwards, the first 11 oz. ran out in 20 seconds, and the next 8 oz. in 25 seconds, which is as 4 to 24 in the same time; the first portion passing out in a compact stream, and the second unconnected, proving that it was the mere weight of the upper portion that caused a larger quantity to pass in a given time, and in a body. To ascertain the precise manner in which the current of water approached the hole for passing out-I fixed with a weight, a small cork to the bottom, by a piece of thread 1 long, thereby allowing the cork to rise half an inch above the pipe, when filled with water. I also placed a piece of cork on the top of the water, half an inch from the side of the vessel; but upon the water being allowed to run out, neither of the corks were drawn towards the centre, until the water had descended to the pipe; from which it appears, the water approached the pipe in a column from the top of the fluid, equal in size to the hole it passed out by, and was, I imagine, supplied from the top in the same manner, till it got down to the pipe, when the corks were drawn to the

centre.

In the next experiment, with the pipe reversed, as in figure 1, same page, 20oz. ran out in 20 seconds, being rather less

than half the time of the former experiment, which can only be accounted for, as Trebor Valentine asserts, by the greater depth of fluid; the ratio of weight or pressure, increasing in a much greater degree, and with it the impetus of emis sion, than the actual weight of the fluid added; that is, if a 20 feet leaden pipe of any bore be filled with water, the lower 10 feet will run out in the time of the succeeding five, or the lower 15 feet, in the time of the upper five-not from the presssure of the atmosphere, but from the weight of fluid increasing upwards in a compound ratio; and in the same manner I account for T. V.'s experiments, as described by his figures 2 and 4, same page.

Trebor Valentine assumes, in his postscript, that melted metals, as fluids, are governed by the same laws as water, with one exception, viz. its expansion on becoming solid, and its (supposed) consequent buoyancy. I, of course, suppose T. V. expresses himself generically, not ambiguously, and if so, it is a wrong conception; for I know of no similarity, except buoyancy, which meltéd metals possess. Melted lead, zinc, tin, or quicksilver, cannot support a solid body of the same density, for two reasons, namely, the melting point of heat with the three first being nearly equal, and the strong affinity they possess for each other when melted; which latter property is one reason for their supporting connectedly or individually, iron, or other ponderous substances. I feel convinced melted iron will not support a solid piece of the same, or of any other metal that can be brought to a state of fusion at a less heat, than the melted iron possesses; but gold or platina, I feel assured, will remain on the surface; for when the melting degrees of heat do not assimilate, the strong tendency, or power of adhesion in melted mettle, sufficiently explains the cause of suspension of a heavier mettle in a solid state. The expansion of congealed water is owing to the air it contains, upon which also in a great measure its buoyancy depends. Yours, &c. G. L. L.

Enfield, Nov, 21, 1831.

TIDES AT OTAHEITE.

Sir,-When I wrote my first article (p. 444, vol. xv.) on the tides at the island

of Otaheite, in answer to that of O. C. F. (p. 405, vol. xv.) I did not at the time consult any authorities. True, I had some years ago read the voyages of Captain Wallis, as well as those of the immortal Cook, and several others; and I was certain, that had any of them assert ed what the Russian navigator, Kotzebue, has done respecting the singular law which the tides at Otaheite are said to observe, it could not have escaped my notice. Perhaps, in candour, I ought to confess, that I felt a degree of unwillingness to believe a statement which, if true, was so perfectly inconsistent with the received theory of the tides; that theory forming one of the pillars which support the law of universal gravitation, to doubt which would, in my opinion, be a species of heresy. But, Mr. Editor, (for I must not conceal any information I am in possession of, even although it should operate against myself), I find that Mr. Bennett's statement to O. C. F. has received what may be considered by some as positive confirmation, in a work lately published by Mr. William Ellis, entitled, “ A Vindication of the South Sea Missions from the Misrepresentations of Otto Von Kotzebue." After quoting Kotzebue's statement, that " every noon, the whole year round, at the moment the sun touches the meridian the water is highest, and falls with the sinking sun till midnight," Mr. Ellis remarks:

"Kotzebue must have paid little attention to the tides, for instead of continuing from noon 66 to fall with the sinking sun till midnight," after six o'clock in the evening they rise, and continue rising till midnight; so that instead of being highest at noon and lowest at midnight, the whole year round, the tide is highest at both these times, and lowest about sun-rise and sunset every day. So uniform and well understood is this ebb and flow of the sea, that throughout the islands, during the whole year, the time between evening twilight, and midnight, is designated by a term expressive of its advancing height, and the hours from midnight to the appear. rance of the morning-star are distinguished by terms descriptive of a corresponding fact."-P.7.

After reading the above, I considered that it would be necessary to examine the subject a little more closely; and, first, I examined several of our best writers on natural philosophy and physical astronomy, to see if any of them in their ac

counts of the tides had taken notice of this seeming anomaly. But I could find none that has done so; they all agree that the tides in the great Pacific do not rise to such a height as they do in some other seas; still that they are abundantly regular. I again read Captain Cook's first voyage to the Island of Otaheite, and if his testimony is to be believed, it will be found to be in direct opposition to the above statement. Captain Cook's ac count of the tides at Otaheite is as follows:

"The tides about these islands (So ciety) are perhaps as inconsiderable as in any part of the world. A south, or S. by W. moon, makes high-water in the Bay of Matavai at Otaheite, but the water very seldom rises perpendicularly above 10 or 12 inches."

From the above short statement it appears, that so far as the Bay of Matavai is concerned, the tides strictly obey the same universal law that they do in every other part of the world. Now, a S. by

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W. moon will make the time of highwater on the days of full and change at the Bay of Matavai to be a little before 1 o'clock A. M. and P. M; and so far this nearly agrees with the information I had from the Scotch mate: but there certainly is a great difference in the two accounts of the perpendicular rise of the water. Besides, let it be remembered, that the great navigator, Cook, on his first voyage, was sent expressly for the purpose of making astronomical observations at Otaheite, and amply furnished with all the requisites for that purpose; he had also abundance of time, as he remained for three months at the island. Again, on his second voyage to Otaheite— But as this communication has already extended to a considerable length, this, and some other information which I have gleaned from some recent voyages to Otaheite, I will make the subject of a future communication.