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"peller to make any manoeuvre requisite in "intricate navigation, and especially on leaving "or entering crowded harbours. I should have "been glad to see these methods experimented "on, or have used them myself if permitted, on "board the Great Eastern, as this ship is the "most interesting problem of modern naviga"tion, and one which involves not only the "speed, distance, and economy of transport, "but also the means of manoeuvring with faci"lity and security this tremendous body, the "largest ever created by man to be moved on "the seas."

pnses, its recovery after submergence is certain and easy. With such advantages as these, it may fairly be asked, what possible objection there can be to its immediate general adoption by telegraph companies and engineers?

HEARDER'S SUBMARINE TELEGRAPH

CABLE. This novel and interesting application of scientific research to the removal of a difficulty that threatened to circumscribe the limits of success in submarine telegraph cables, and which has excited of Lite considerable interest in the minds of telegraph engineers, was last week submitted by the inventor for the approval of the judges of the Royal Cornwall Polytechnic Institution, at their annual exhibition held at Falmouth. Their entire satisfaction with the efficacy of the plan, and their perfect concurrence in the soundness of Mr. Heanler's scientific reasonings, were manifested by the unanimous award of the Society's first class silver medal. Of the many modifications of which Mr. Hoarder's plan for obviating the effects of induction is susceptible, he appears to have selected the following:— The wire strand, which is five or six times as large as that of the Atlantic cable, is first coated with a number of strands of a very superior flax twine, incorporated with an adhesive insulating medium, which binds them firmly together. They are laid on in a very long spiral direction, the reverse of the twist of the wire; this is secondly coated with a layer of guttapercha, and, thirdly, with another layer of twine laid on in the same manner, but in a direction opposite to that of the first. The whole is subsequently covered with two layers of guttapercha. In other samples the first layer of twine next the wire is omitted, and one or two layers of twine and adhesive composition are laid on after the first coating of gutta-percha, and are subsequently covered with two thicknesses of gutta-percha.

Mr. Hearder's patent mainly consists in the employment of fibrous materials between the wire and the insulating medium itself. The advantages of it are stated by Mr. Hearder to be —1st. The reduction of the disturbmg influences of inductive action to a minimum upon wellrecognised electrical principles, which have been submitted to the test of experiment. 2nd. Improved insulation: the heavy hydraulic pressure to which the submerged cable would be subject, not only prevents the possibility of fissures occurring in the adhesive insuLiting composition, but any fissures in the gutta-pej-cha itself would be effectually filled or closed over by this composition, thereby rendering the chance of leakage from damage, resulting from rough usage to the cable, infinitely less than with gutta-percha alone. 3rd. Increased strength: every strand of twine possesses a breaking strain of about 40 lbs., consequently, as the samples contain from 25 to 50 of these strands it is evident a breaking strain of from 1,000 to 2,000 lbs. is added to that already possessed by the cable itself without the twine. 4th. Extreme lightness: the specific gravity is from 1*3 to 1-4, varying with the size of the conducting wire. 5th. Perfect facility of recovery after submersion: as the cable will support a weight five times greater than that of any portion of its length which can be submerged in depths available for telegraphic pur

TIIE BRITISH ASSOCIATION FOR THE

ADVANCEMENT OP SCIENCE. At the annual meeting of the British Association for the Advancement of Science, lately held at Aberdeen, the following papers were received in the Mechanical Science Section (Section G.), of which the Rev. Professor Willis, F.R.S., was the President.

Thursday, Sept. 15.

1. Report of the Committee on Steam Ship Performance. [We have been favoured with a copy of this •report, and if we can extract anything useful from it for our readers, will not fail to do so.]

2. Admiral Moorsom.—On the Performance of Steam Vessels. [A copy of this paper has not yet reached us; we may state, however, that it consisted mainly of statistics.]

3. J. Oldham, C.E.—Report of the Progress of Steam Navigation at Hull. [This paper is published in our present number.]

4. Charles Atherton, communicated by H. Wright. — On Mercantile Steam Transport Economy, as affected by the Consumption of Fuel. [We have been favoured with a copy of this paper, and shall either publish or notice it in an early number]

5. J. Macquorne Rankine, LL.D.—A Condensed Abstract of Experiments, by Messrs. R. Napier and Sons, on the Strength of Wrought Iron and Steel. [This paper will be published in an early number.]

6. Donald Bain, communicated by H. Wright. —On Harbours of Refuge. [This seems to have been a speech rather than a paper; at any rate we can at present get no report of it.]

Friday, Sept. 16.

1. P. Le Neve Poster.—Report of the Patent Committee. [Published in the Mechanics' Maoazine for last week (Sept. 30.)]

2. William Fairbairn, F.R.S.—On Experiments to determine the Efficiency of Continuous and Self-acting Breaks for Railway Traiiu. [This paper is published in our present number.]

3. J. F. Bateman, C.E., F.R.G.S.—Description of Glasgow Water Works. [This was a verbal description of drawings, of which no report has reached us.]

4. R. Aytoun.—On a Safety Cage for Miners. [This was, we believe, a description of an invention recently patented by the author, the specification of which has been published in due course by the Commissioners of Patents.]

Saturday, Sept. 17.

1. J. F. Bateman.—On the Result of Boring for Water in the New Red Sandstone near Shifl'nall, in the County of Salop. [This is published in our present number.]

2. W. Robertson, communicated by Peter Spence.—On a Patent Chain Propeller. [We have a copy of this, and will publish it if we find it of sufficient interest.]

3. Admiral Paris, C.fi.—On the Manoeuvring of Screw Vessels. [This is abstracted in a leading article of our present number.]

4. Arthur Taylor, communicated by H. Wright. —On the True Action of what are called Heat Dilfusers. [This will be published in an early number.]

5. A. Batten.—On a Boat Lowering Apparatus. [This was a paper on Mr. Clifford's apparatus; we hope to find space for it hereafter.]

6. E. A. Wood.—On a Mode of Suspending, Disconnecting, and Hoisting Boats attached to Sailing Ships and Steamers at Sea. [This paper was not, we believe, read. We may state, however, that it consisted mainly of a description of the apparatus described and illustrated at page 105 of the Mechanics' Maoazine for the 12th of August last.]

7. D K. Clark, C.E., communicated by H. Wright.—On Smokeless Coal-burning Locomotive . Engines. [This is published in our present number.] Monday, Sept. 19.

1. AbbS Moigno.—On a New Gas-bnrner.

2. AbVi Moigno.—On an Automatic Injection for Feeding Boilers, by Mr. Giffard.

3. Abbe Moigno.—On a Helico-ineter, an Instrument for Measuring the Thrust of the Screw Propeller.

4. Abbe Moigno.—On an Application of the Moving Power arising from Tides to Manufacturing, Agricultural, and other Purposes; and especially obviate the Thames nuisance.

[The above four papers were written in too imperfect English to find a place in our pgaes.]

5. Alexander Gibb.—Descriptionof the Granite Quarries of Kincardineshire. [We have a copy of the paper, which we may perhaps publish in an early number.]

( Alexander Allan.—On Gas Meters. '\ Alexander Allan.—Description of an Improved Method of Obtaining a True Liquid Level. [We have a copy of this paper, but not (at present) of the drawings which illustrated it.]

7. John Robb.—On the Comparative Value of Propellers. [This paper, however fit for the British Association it may have been, has no sort of claim to be published in our columns. The invention advocated in it is a very old one, and the views of the author are not such as to help it at all.]

8. Alexander Gerard.—An Experimental Illustration of the Gyroscope. [This does not admit of publication.]

Tuesday, Sept. 20.

1. William Fairbairn. — Experimental Researches to Determine the Density of Steam at Various Temperatures. [An abstract of this paper will he published in an early number.]

2. J. Elder.—On the Steam Machinery of the Callao, Bogota, and Lima. [We have a copy of this, which we may publish in an early number]

3. J. P. Joule, LL.D., F.R S.—On Surface Condensation. [This was little more than a memorandum; no copy of it has yet reached ns.]

4. Mr. Rettie.—On a Submariue Lamp. [An abstract of this will be published in an early number.]

5. G. Johnstone Stoney.—On the advantages of the 40-inch Metre as a Measure of Length. [This is published in our present number.]

6. Andrew Henderson. — On India River Steamers and Tow-boats—giving an account of their improved construction for light draft, capability for cargo, and fittings, conducive to manageability in shallow rapid rivers, &c, and of the practical value of the Dynamometer in showing the resistance of vessels in tow, at different speeds and loads, with the result of testtrials made in England. [We have not yet received a report of this paper, but have been informed that it is in the main a resume of what Mr. Henderson has before read and published on the same subject.]

7. G. Hart—On Gas Carriages for Lighting Railway Carriages with Coal instead of Oil. [This paper describes a method by which coalgas may be applied to railway carriages. The author does not seem to be aware of what has been before proposed and done in this respect. We will, however, publish it if we find it will be of any value to our readers.]

8. Captain J. Addison.—On Coal-pit Accidents. [This paper recommends the carrying out of an idea which occurred to the gallant author on seeing a man vending children's balloons in the Rue do Rivoli, Paris, viz., that of employing similar balloons to test the atmosphere of mines, the presence of carburetted hydrogen being detected by the balloons not rising to the top of the mine, chamber, or passage, and the presence of carbonic acid by their not sinking to the bottom.]

9. H. Johnson. — On a Deep-»ea Pressure Gauge. [We have a copy of this paper, and shall publish it in an earlv number.]

10. Mr. Davies, F.R.S.A., F.L.S.—On a Patent l)isc Pan fur Kvapurating Saccharine Solutions and other Liquids at a Low Temperature. [\Ve shall probably publish this in an curly number.]

11. Adnm Topp.—Various Modes of Fire Es capes, lioats, &e. [This miscollaneona affair has not reached us in any form.]

There were a few papers which will be of interest to our readers read in other sections of the Association; these wo shall publish in due time.

Off EXPERIMENTS TO DETERMINE THE
EFFICIENCY OF CONTINUOUS AND

SELF-ACTING BREAKS FOR RAILWAY
TRAINS.

By William F.ubbaibx, C.E., F.R.S., &c.*

Of late years various improvements have been introduced upon railways, to diminish the dangers of travelling, and attention is now specially directed to the increase of the retarding power for trains by various kinds of breaks. From an early period in the history of railways, it was seen that few objects were more important for ensuring the Hccurity of passengers, and reducing the loss of time occasioned by stoppages, than the attainment of some moans of destroying the momentum of trains with case and rapidity ; that is, in the least time and in the shortest distance. The less the time requisite to break a train, tho longer the steam may be kept on in approaching a station and the less is the loss of time in stopping. And the shorter the distance in which a train can be brought to a stand, the loss danger is there of collision with obstructions on the line perceived not far oil' ahead. It is already allowrd by many of those connected with railways, and Las been expressly stated by the Lords of the Committed of 1'rivy Council for Trade, that the amount of break power habitually supplied to trains is in most ca-ics insufficient, and their Llrdships enumerate thirteen accidents from collision occurring in 1858, the character of which they consider would have been materially modified, if not altogether prevented, by an increased retarding power under the command of the guards of the trains.

Upon this subject the most important communication hitherto made Inn been the Report prepared by Colonel Volland for the Railway Department of the Board of Trade, and containing a large number of experiments with heavy trains at high velocities. The breaks with which Colonel Yolland experimented were those which, as im

{trovements on the common hand break, have litherto commanded most success. These were tho steam break of Mr. McCcmnel, tho continuous break of Mr. Fay, the continuous and self-acting break of Mr. Newall, and tho self-acting bull'er break ofM. Gucrin. The general conclusions to which Colonel Yolland was led by his experiments resulted in the recommendation of the break of Mr Newall; and for heavy traffic, a provisional recommendation of the break of M. (tuerin.

From a misunderstanding caused by this Report of Colonel Yolland arose the necessity for some further experiments on the similar breaks of Mr. Fay and Mr. Xewall; and these I was called upon to arrange and catry out, by the direitors of the Lancashire and Yorkshire Railway. I propose to lay before the Association a brief abstract of these experiments, with some remarks upon the conclu sious to which they gave rise.

It will not be necessary h«re to describe minutely the details of the construction of these breaks. They consist essentially of a-serics of breik blocks acting upon every wheel of the carriages of the whole train or some part of the train, the break blocks being suspended as llajis or placed on side bars beneath each carriage, us in the ordinary arrangement of the guard vans, lint whereas it would be both expensive and inefficient to work these breaks with a guard or breaksman to each carriage, both Mr Fay's and Mr. Xewall's patents provide for a continuous shaft, carried the whole length of the train beneath the framing, and with suitable jointed couplings between each

•A paper read to the British Association, 18W.

pair of carriages, so that they may be undisturbed by the rocking motion of the train or the action of the buffers. In this way the whole of the breaks may be worked by a single person at either end of the train communicating his power to each break though the agency of the continuous shaft.

A'jain, there have been applied, in the first instance by Mr. Newall and subsequently by Mr. Fay, powerful springs beneath each carriage, connected with the arms of the rocking shaft, by moans of which the breaks arc made to act instantaneously throughout the train, on the release of a catch or disengaging coupling in the guard's van. Tho valua of this provision for the im mediate and simultaneons action of tin whole of the breaks, in cases where an obstruction is porceived upon the line, will be at oncd evident. It is one of the most important features of these breaks.

In carrying out the views of the directors of the Lancashire and Yorkshire Railway Company, it wai arranged, in order to test the relative efficiency of these breaks, to hive a series of experiments upon the Oldham incline of 1 in 27 on this gradient. A train of carriages fitted with Mr. Newall's self-acting slide breaks, and a similar train fitted with Mr. Fay's continuous flap breaks, were started in turn, and after having passed over a measured distance by the action of their own gravity, the breaks were applied, and the distance along the incline in which the trains were respectively brought up wa-i carefully ascertained, as a measure of the retarding force of each. The trains employed consisted of three weighted Carriages each, and having been placed upon the incline, they were started by removing a stop. Having then descended a previously measured dis-' tance with a uniformly accelerating velocity, they passed over a detonating signal, which conveyed notice to the guard to put on the breaks. Then the train having been brought to a stand, the distance from the fog signal to the point at which the train stopped was measured, and the train brought back for another experiment. In this way it was easy to obta'n a:i initial velocity of 50 feet ft second, or 35 miles an hour, before applying the breaks.

Unfortunately the day upon which these experiments were made proved misty and foggy, with rain at intervals, so that the rails were in the veryworst condition for facilitating tho stoppage of the train. The significance of this fact will be seen on comparing the retarding power of the breaks in these experiments with those made in fine weather.

Reducing the results, we find that the retardins; force exerted by each break in terms of a unit of mass, was equivalent to tho numbers in the following table: —

EXPERIMENTS OX THE OLDIIAM KfCUXK.

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The general result of these experiments gives a ru'arding force of 1'71 Ibs. per nnit of mass for Mr. Newall's break, and 1-83 for Mr. Fay's. Or, in other words, Mr. New-all's break exerted a retarding forco of 121-3 Ibs. per ton weight of the train, and Mr. Fay's a retarding force of 12'J Ibs. oer ton.

I afterwards arranged fot some further experiments at Southport upon a piece of level rail between that town and Liverpool. The speed requisite in this case had to be obtained by the aid of an engine, which was detached by a slip coupling at tho instant of applying the breaks.

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In this case we have a retarding force per nnit of mass equivalent to 5-19 Ibs. in Mr. Newall'n break, and 6'7 11)3. in Mr. Fay's. Or, in other words, tho retarding force of the slide breaks of Mr. Newall, from eight experiment*, at velocities varying from 35 to GO miles an hour, was equivalent to 382-G Ibs. per ton weight of the train. Tho retarding forco of Mr. Fay's slida break from eight similar experiments, at velocities from 33 to G3 mile} per hour, was equivalent to' Ib.s. per ton weight of the train.

FLAP BREAKS—ENGINE DETACHED.

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These experiments give for the retarding force of Mr. Newall's ilap break 6-32 Ibs. per unit of mass, and for Mr. Fay's, 6-87 Ibs.

Or, in other words, the retarding force of Mr. Newall's flap break, from three experiments at velocities varying from 50 to 51J miles per hour, was equivalent to 110-3 Ids. per ton weight of tho train.

The retarding force of Mr. Fay's flap break*, from three similar experiments, was -iOS'6 Ibs. per ton.

We may illustrate the general bearing of these experiments by estimating from an average of the whole experiments the distance required to stop a train fitted with these breaks, and detached from the engine:—

A train would be stopped at a velocity of 20 miles an hour in 23'1 yards. 30 „ „ 52!) „

40 „ „ 93-8 „

50 „ „ 1-168 „

6J „ „ 211-5 „

This last table exhibits, in a very clear manner, the advantages of this class of breaks, in which the whole weight of the train aids in destroying tho momentum of the mass instead of tho weight of one or two guard vans only. It may be impos sible in long trains to apply these breaks to everv carriage; but at all events, in the ordinary traffic-. three times the present amount of break power may be employed with ease.

On tho score of economy, also, the system appears to encourage its application. From experiments which have been made it appears that thu ivear of the tyres a far more uniform and equal. because the springs may be so adjusted as not to cause the wheels to skid. Tho manager of the

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It will be observed that on most through lines that the trains travel on some portion of the distance at the rate of CO miles an hour; and in the event of an obstruction half-a-mile in advance a collision would be inevitable unless the driver has the power and the presence of mind to act with promptitude. Now, at CO miles an hour there is only 30 seconds, or half-a-minute, to effect that object, and it is quite impossible to apply the breaks in their present state before the train—in such a precarious position—is in actual contact. Assuming, however, that breaks upon the principle of Newall and Fay were attached to the engine as well as the train, and that the driver had the power of instantaneous application by liberating a spring, it is evident that instead of the train dashing forward to destruction, the momentum might bo destroyed in a distance of less than BOO yards, and that without injury to life or property. Besides, the application of the electric telegraph, which prevent* on most through lines more than one train being on the line between the stations, is a gTcat additional security, and that united to the continuous break applied to the engine as well as ike train would, when united to a more perfect system of signals, render collision next to impossible.

ON

THE SUPPLY AND PURIFICATION

OF WATER.
Br Thomas Spkmcsr, Esq., F.C.S., &c.9

TiiE author of this paper set out by stating that
from an extended practice for a number of years
in relation to the chemistry of water for the
supply of towns, ho became convinced that the
available quantity of pure water in these islands
was decreasing, whilst it was evident the demand
for this primary necessary of life was undergoing
an annual increase. In short, that in the more
cultivated districts the supply was every year
becoming lets capable of meeting the demand.

From continuous personal observation of many of the water-bearing districts of Great Britain, he bad now found many shallow springs dried up, or gradually becoming so, whilst the beds of small streams, where water was formerly known to flow pretty regularly, were almost dry, except in times of flood. This had a corresponding effect on the depth of the water of most rivers, but was especially felt of late years in those that were navigable.

The bearing of this state of things on our available water was to increase the quantity of its organic impurity, inversely with the amount of its supply. These effects he would show were chiefly due to increasing drainage.

An additional and most important source of the impurity of river water arose from the now legalised efflux of excreinental matters into common sewers, and thence into rivers, by which they were rendered equally fertile sources of disease to the cesspools they had superseded. In short, wherever population was, running waters wore becoming more and more polluted with the

matters which formerly went to maintain the
fertility of the soil. Nor was it necessary to re-
mind the members of that section that agricul-
turists had to resort to another hemisphere to
make up the deficiency. So obvious had this evil
become, that the aid of chemistry had been
universally called for to devise some means of
entrapping the riches which were thus squandered
in the ocean.

Although prophecies as to the results of con-
temporaneous operations were attended with con-
siderable risk, yet he would venture to predict,
that the chemical efforts now being _ made to
utilise sewage matters must prove abortive, simply
because they were commenced at the wrong end
of the sewer. That modes were known to chemists
fully equal to the extraction of all the nitrogenous
and phosphoric constituents of diluted sewage,
there could be no doubt.

The real question, as regarded any of these operations, was not as to whether it coulil be done, but whether, when done, the products would repay the cost of obtaining them—a consummation which was far from probable. At the same time the chances of success would be found much greater if the attempts to utilise these matters were undertaken at less distance from their source, and previous to what he regarded as their destructive dilution Kith water. As it was, however, this had the effect of causing the inhabitants of towns to resort to distant quarters for water, to replace that which they formerly obtained in sufficient abundance from the rivers.

As already stated, shallow springs were becoming extinct, whilst supplies from wells could only be obtained by carrying them to greater depths, and those had to be sunk far apart, to ensure an extended conoid of percolation. Mr. Spencer then proceeded to show that the causes of this general diminution of spring water was almost entirely duo to the vastly increased drainage that had taken place of late years. The greater part of the rain that was formerly allowed to percolate the substratification, and thence issue at lower levels as spring water, was now carried off the land by means of deep drainage, and drain pipes, into the adjoining brooks in a few hours. The contrast between this and the former state of things was desciibed as being not unlike that witnessed after rain had fallen on two roofs, the one thatched, the other slated. For hours after the last shower water trickled from the eaves of the thatch, whilst a few minutes served to obliterate all traces of moisture from the slates.

But in addition to this, the same condition of things had the important effect of diminishing our rainfall as well, so that not only was it rapidly carried oil' the land, but as a direct consequence, every year drainage had less water to deal with. This result arose as follows:—The larger amount of dry surface resulting from excessive drainage had two distinct effects, each dependent on the other. One was to diminish the amount of evaporation, nnd thereby cause fewer clouds, whilst the same absence of moist surfaces prevented clouds from other quarters being attracted, consequently their aqueous contents were not so liable to be discharged on the now well-drained tracts as formerly.

Though the operation of these circumstances on our climate was described at considerable length, yet this part of the subject was alone so extensive as to cause the author to leave mauy important points untouched. In concluding the first part of his communication, that he might briefly exemplify the principles he had set forth, Mr. Spencer put it to his auditory, if, when speaking of formerly moist or ill-drained districts in recently discovered tracts, they did not constantly hear of the meliorating influence which had been effected on climate by cutting down forests, and draining marshes, nnd, was not this always foU lowed hy a lessening of rainfall I And again: if these sources of evaporation were thus cut off, was it not obvious that the natural process of cloudforming must.to that extent be decreased, and

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were not most observers agreed in opinion, that clouds are attracted wherever there is wide-spread moisture, and as a consequence, is their rain not discharged more abundantly and frequently at those parts of the surface, than where moisture to the same extent does not exist?

In corroboration of what had been stated, he added, that the most reliable meteorological observations of the lost forty years exhibited a continuous decrease of rainfall, at least in the more southern parts of this island; whilst during tho same period the extent of the drainage area had been steadily advancing. The author had no intention of doubting that the benefits of improved drainage were of a high character, and almost equally so those arising from the absence of accumulations of filth near our dwellings. Both were the inevitable results of our advancing civilisation, though each might be made to undergo some wholesome modification. Meanwhile, great as their benefits undoubtedly were, his present object would be attained if he succeeded in calling attention to the vast though hitherto overlooked cost at which they were obtained.

His opinions as to the results of drainage, together with the probable effects of sewer water on the quality of our domestic supply, were first published by the author in IS 10. Siuce that period all his very ample opportunities for practical observation have added certainty to tho opinions he had then set forth. It being thus evident that the quantity, as well as the general quality of our water supply was rapidly deteriorating, it struck him that some efficient and cheap mode of effecting its purification would bo attended with great public benefit. According!/, in 1851, he began to devote himself to the subject, which he had now brought, he trusted, to a successful issue.

At the commencement of his researches, the opinions of all the authorities with regard to tho probability of purifying water by artificial means, were summed up at the conclusion of the report drawn np by the Government Commissioners, "On the supply of water to the Metropolis." These gentlemen there said : —■ " That water cannot be deprived of matter held in solution by any practical modification of the process of filtration." This was the stat#of the subject when entered on by him. His object, from the beginning, was to discover the mode by which nature converted impure coloured surface water into colourless spring water, the operation being apparently one of filtration. His first experiments were made with a view of throwing some light, if possible, on the philosophy of filtration as ordinarily practise J, he having some renson to believe the process, when most effective, did not so much depend on mechanical principles ns was generally supposed. To determine this point, a long series of very interesting experiments were related, which resulted in showing that properly conducted filtration (i.e., where the gravitating power of the water is not in excess) is dependent on a lateral attractive action exercised by the saud or other media through which the process is performed, this being in addition to the downward action of gravitation. His next object was to discover what bodies in nature exercised this newly-discovered attractive power the best. After trying a number of experiments with various descriptions of rocks and minerals, all of which were described to the section, he found that those containing protoxide of iron (even where it was chemically combined with other substances) effected tho filtration of water better than any other. Acting on the idea thus suggested, he found the same oxide, when isolated in the state of "magnetic oxide," not only to free it from turbidity more effectually than an equal thickness of sand, but to effect its decolouration with marvellous rapidity: whilst the other earthy substances entering into the composition of the same rocks, such as silica and alumina, were, in the latter respect, perfectly inert by themselves. From this it appeared evident that the protoxide of iron— as magnetic oxide—a substance which enters into

the composition of so many rocks, was one of na. ture's chief agents of purification. Here the author referred to a series of experiments he had made, showing that the commonly received opinion, that light and air aloiie effected the purification of water, was erroneous. For example, he had put coloured bog water into shallow glass pans, in which it was fully exposed to both these agencies for several weeks—evaporation beingcompensated by distilled water—but without any change being apparent in its colour. This result, so contrary to what might have been expected & priori, led him to refer the natural process to the agency of some other body wb,ich probably exercised a catalytic action on the atmospheric oxyge'n, and thereby induced this gas to combine with the noxious impurities existing in the water. Nor was he mistaken in this surmise, as the rasults so amply related in the paper, together with the experiments, exhibited to the section, sufficiently attest. A very striking one was made with some bog water, much darker in colour than ordinary porter, which had been procured from the soakings of an Aberdeeushirc peat bed. This water icat deprived of colour almost instantaneously by mere contact with the oxide.

To appreciate this result it is to be remembered that no known agency has been able to effect a similar one before. Since soft water has become so much an object for manufacturing purposes, to effect the decolouration of that of bogs had remained a problen unsolved by chemists. Not only was it now evident that this water could be deprived of all trace of colour, but it was rendered bright, clear, and perfectly free from taste. Several who partook of it pronounced it to be equal in these respects to spring water. Above all, the means by which the charge waseffectedwere soexceedingly simple. For example, the coloured water was poured into a glass vessel containing a layer of aboat five inches of equal parts of coarse sand and a hard ferruginous substance, perfectly magnetic, on which the water issued forth with great rapidity, perfectly colourless.

The action of the oxide, however, was far from being confined to the decolouration of bog water; that experiment had only been brought forward beduise it could be strikingly exhibited to a public assembly. On the cAtrary, it equally affected every impurity to which water was subjected— even that of the London sewers had been rendered harmless, and void of all odour and taste by the same means. Besides which, it had resulted from the experiments of Professors Brande and Clark, that soft water treated by the magnetic oxide had no action on lead.

Perhaps the most extraordinary circumstance was, that the magnetic Jittering medium itself suffered »o deterioration after any period of operation. Its province was confined to forcing the oxygen resident in the water into combination with the colouring matter, and thus converting it into carbonic acid, which gas, it need hardly be said, conferred freshness and salubrity on all waters in which it was found. In this result the occult action of catalysis was, for the first time in the history of science, brought at will into useful every-day operation: in explanation of this extraordinary action, the author now entered at some length on the recerved notions of what was really to be understood by the term "catalysis." He thought it might be satisfactorily shown that the substances inducing this action did so in virtue of their power to alter the molecular arrangement of the bodies they acted upon—as a magnet alters the arrangement of iron filings, even at a distance. He believed he was in a position to show, however, that the phenomenon was strictly identical with electro-polarisation.

In the experiment he had exhibited, there could, he believed, exist no doubt that the magnetic oxide of the filter had the power of attracting oxygen to its surface, and when there this gas necessarily became polarised. Whilst in that state, and only whilst in that ttate, it combined with the organic colouring matter to form a new substance. But the most startling circumstance

he had to relate was, that the oxygen ipfan in this state of polarity was neither more nor less than ozone—that fugitive body, of hitherto doubtful origin, which had become so much identified of late with atmospheric salubrity. This novel proposition was illustrated by an equally novel and certainly most convincing experiment, as far as it went. We are unable to give its details farther than by stating that it exhibited a larger amount of oxygen converted instantaneously into ozone by the action of the magnetic oxide, on an alco holic solution of gum guiacum, than, perhaps, had ever been witnessed in the same compass before. Though the President evidently had not leant to the author's theory, this unlocked for proof of it elicited his admiration. Mr. Spencer stated, however, that this was only one among many modes he possessed of demonstrating the same fact, viz.:—that ozone was polarised oxygen.

For example, a still stronger proof was cited, viz.:—that the poles of a galvanic battery immersed in the guiacum solution of alcohol produced ozone in the same manner, out only at the oxyyen pole. But what he ventured to believe amounted to a confirmation of this view was, that a similar effect was that the battery did not produce this effect in a solution with absolute alcohol; water was therefore essential in order that its oxygen might undergo polarity, or in fact, ozonifieation. Mr. Spencer further stated, that according to his experiments, he had found most natural substances that contained protoxide of iron exercised this power of ozonifying oxygen. Even if this now important oxide was locked up in chemical combination with other bodies, still the power was more or less exercised through the solid covering. The existence of ozone in the atmosphere, therefore, need be no longer a problem. He had proved by his experiments, that air whilst passing over substances of this character became ozonified by contact alone. Henceforth we could account for the salubrity of some winds as compared with others. It would now be evident that the adventitious electricity of thunder storms had but a small share in producing ozone in sufficient quantity for the purposes of nature. But the ferruginous suboxide was not the only one that exercised this important function, as several other metallic sub-oxides which he enumerated partook of the same power, though in less degree. Per-oxide (ordinary rust), on the other hand, or metallic iron, was perfectly inert. He also found that several gum resins exercised a similar power, though in lower degree, over oxygen.

Mr. Spencer now gave an account of a new compound magnetic body which he had succeeded in making to better enable him to carry out the purification of water on a large scale. Though the magnetic oxide he had first obtained from the white carbonate of iron was very effective, yet it had a tendency to be reduced to powder by attrition. He became apprehensive therefore it might ultimately interfere with the rapidity of his filtering operations. This led him to seek some mode of procuring a harder and less friable body. After various experiments he had been successful beyond his anticipations. By very simple means he had formed a magnetic body from the hitherto refractory Cumberland hematite. The new substance consists of iron, oxygen, and carbon—an equivalent of each—its atomic number is therefore 42. Specimeiis of the new body were exhibited to the section. It appeared very hard, and when polished had a black metallic lustre. It was said to be as incorrodible as gold or platinum, and is highly magnetic. Its purifying powers were stated to be very great. It can be manufactured very cheaply. Mr. Spencer, as its discoverer, had named it protocarbidc of iron.

The President (Dr. Lyon Playfair), at the close of the paper, was sure the section would feel much indebted to Mr. Spencer for the valuable nature of the practical results he had laid before them. Though much struck with the ozone-forming experiment in support of the theory, yet he, the President, hardly felt himself at Kberty to give his adhesion fully regarding this view of the na

ture of ozone. There was another mode of testing the matter, however, which he named, and which, if successful with the magnetic oxide, might carry more conviction to his mind. Mr. Spencer stated that he had not considered the mode named by the President as being so good a test of the presence of ozone as the one he had brought before the section.

At the following meeting of the section, however, this experiment was successfully performed by Mr. Spencer, in the presence of the President, thus affording an additional proof that ozone U only polarised oxygen, and that nature is not confined to one mode for its production.

Copious as this abstract appears, yet we hare been obliged to omit several equally interesting topics embraced in the original paper.

COAL-BURNING LOCOMOTIVES, "r. K.claek's System Op coAt-nr/HXiNa Without

SMOKE, nr THE METHOD OP STEAM ntDUCTID

Ain-CFHBKNTS, APPLIED TO THE LOCOJfOTTVTB

ENGINES OF THE GREAT NOBTH OP SCOTLAND

RAILWAY."

By Daniel Kikneae Clahk.*

The substitution of coal, as fuel, for coke in locomotives, is not only felt to be a commercial necessity for the reduction of expenditure, but w also discovered to be perfectly practicable as a mechanical problem in conformity with the conditions laid down by the railway Acts of Parliament that railway engines shall consume their own smoke. The means of doing so, to be adaptable to a locomotive engine, must be simple in design, facile of application to existing locomotive stock, easy to manage, easy to maintain, efficient in promoting the combustion of coal without smoke, keeping up the steam, and saving expense.

These desirable qualifications the writer believes belong to this system of smoke prevention. The whole apparatus is external to the fire-box, and therefore not exposed to heat; and it U controlled in the most perfect manner by a single stop-cock. Air is admitted above the fuel bygone or more rows of tubes inserted through the walls of the fire-box, and jets of s'team are projected through the air-tubes from nozzles ,', th inch diameter, in small steam pipes, placed outside the fire-box, to increase the quantity and force of the air admitted above the fuel in order to consume the smoke. The jets of steam are used principally when the engine is standing, with the aid of a light draught from a ring-jet in the chimney, to carry off the products of combustion, and they may bo shut off when not required. The supply of air through the tube may also be regulated by dampers.

The grate-bars are placed close together, with. narrow air spaces, and the ash pan and damper are lightly fitted. The level of the fuel should at all times be below the air-tubes.

This system is working with entire success on the engines of the Great North of Scotland Railway, at Aberdeen. It is also successfully at work daily (amongst other lines) on several of the engines of the North London Railway, where, as a Metropolitan line, the regulations against smoke nuisance are rigidly enforced. It requires a leas weight of coal than the engines formerly required of coke for the same duty; and thus saves more than the whole difference in the price of the two fuels.

The locomotive engine has been variously cnt up and mangled in order to suit the views of designers for the combustion of coal without smoke. In the plan before the meeting, the original type of engine promulgated by Mr. Stephcnson, and at this day universally adopted and unsurpassed, is preserved intact; and the locomotive is thus rendered a complete and perfect machine, and entirely meets the great railway necessity of the day—the perfect combustion of coal in railway engines.

• Britkh .Uijciation, ISM.

*Citcr;ifurc.
—•—

Our Engines of War, and How lee Got to Nate
Them. By Capt. jEKVis-WniTE Jebvis, M.P.,
Royal Artillery. London: Chapman and Hall, 103
Piccadilly. 1853.

As a rapid superficial sketch of the progress made in the production of great :md small guns this work has many merits, alth ugh its title is undoubtedly too comprehensive and its price too high. The author, known bed re for his " Manual of Field Operations," his treatise on " The Rille Musket," and his speeches in Parliament on similar subjects, here gives us only a hundred and eight small pages of matter in very large type, nnd it is hardly fair, we think, to the reading public to label such a brochure with the broad and sounding title, "Our Engines of War, and How we Got to Make Them," and to charge six or seven shillings (as is done, if we remember rightly) for it. Many of our engines of war are not mentioned at all in the book, and others are passed over very lightly indeed. It is the publishers, however, we presume, rather than the gallant author, who are responsible for the prico and title, and it is as a warning to them that we express dissatisfaction on these points. In other respects they have turned the work ont of hand very satisfactorily, the type, woodcuts, &c, being of the best kind. It is due to the author to say that he has made his work very interesting,-and has displayed great intelligence in dealing with tho various subjects that he has considered. Nor can wo refrain from congratulating the public upon tho excellent temper and wisdom displayed in the work. There is no jealousy of inventors, no distrust of non-professional men to be found in it; but on the contrary a sound spirit of progress, and a hearty love of improvement manifested throughout. When wo remember that the author holds a high military office—that of superintendent of our small arms department—we cannot but bail such evidences of enlightenment with pleasure. Nor is Captain Jen-is alone in this respect. From a report which appeal's in another page it will be seen that Colonel Dixon, who has charge of tho works at Enfield, has just been evincing a similar spirit in connection with the Association of Foremen Engineers. We gladly accept such facts as proofs that the old and bad feeling of military exclusiveness, which has cost us so much, is declining, and as omens of its speedy and complete extinction.

T/w Journal of the Roj/al Agricultural Society of England. Volume XX., Part I. ISo'J. London: John Murray, Albemarle-street. Tnis journal is very high-priced, hut it is worth all that is charged for it. In the present part we have no less than fourteen articles, some of them of a most valuable nature. Those on the preservation of timber, the application of liquid manure, American methods of economizing labour, and the cultivation of land by steam, deserve the special attention of our readers.

The Drawing-Boom Porlrait Gallerg of Eminent Personages. With Memoirs bv the most able Authors. 1859. Second Series. The London Joint Stock Newspaper Company (Limited), 1U9 Strand; West-end Branch, 122 Rcgent-strcct. Without the slightest approach to exaggeration it may be said that a book more suitable for a drawing-room table than this does not exist. It contains portraits of at least forty of the most notable persons of the day—statesmen, clergymen, engineers, artists, orators, singers, and so forth; nnd such portraits as never could be obtained until now at any price, and even now can be obtained nowhere else for twenty times the sum for which they are here supplied. The highest photographic art has guided the highest art of the engraver in their production, utid hence we have a result which is both splendid and unique. If the price were many times what it is we should recommend every reader of ours who cin afford to put a handsome book on his drawing-room table to pnt this (and the previous volumelikewise) there.

The Tlteorgof Compound Interest an I Annuities, Kith Logarithmic Tablet. By Fkhuu Tiiuxa.y, of the Societu Credit Mobilicr of Paris. London: Lockwood and Co., Stationers'-hall-court. 1859. Tina is a very ambitious book of its kind, and bears evidence of great research. Fortunately it does not lie within our duty to examine deeply into a financial work, but wo may nevertheless say that we have taken the trouble to go through some of M. Thoman's mathematical investigations, and to glance generally through the book, and our impression is that he has produced a very original and valuablo work. Professor De Morgan, who speaks with some weight on such a subject, and who has looked into the volume, thinks highly of it.

Mr. Goidsworthg Gurncg's Account of the Invention of the Steam-jet, or lilast; an>l its Application to Steam-boats and Locomotive Engines. London: S. Barclay, Castle-street, Leicester-square. 1859. Mu. Goldswokthy Gurjjfy here claims for himself an invention which Mr. Smiles has attributed to the late Mr. George Stephenson, and claims it, as we think, with much apparent reason.

LIST OF NEW BOOKS.

Aston's Income-tax Tables, New F.clit., 3s. 6d.

Blcnkarn's Ilriti-h Timber Trees, 5s.

Clejrp, on The Manufacture of Coal-Gas, Third Partition,

31s. (Id. Kennedy's Notes on the Defences of Great Britain, Fourth

lvlition, 2s. (id. M. Even's Culture of the Peach and Nectarine, 3*. Cd. Turner's Domestic Architecturein England, Vol. 111., 30*. Wilson's Our i-'arm Crops; l'art I., Wheat Crop, Is.

THE PROGRESS OF STEAM NAVIGATION

AT HULL.

By James Oldbas, Esq., Hull, M.I.C.E.*

Fob generations past Hull has been noted for its Greenland and Davis Straits fishery, and for many years this has constituted the chief feature of tho port. Within the last two or three years steam has been put into successful requisition to aid the dauntless and hardy mariner in the pursuit of this hazardous calling, and now we have several screw steam-ships employed; and although some of them are fitted with comparatively small power, they have proved to be possessed of great advantage in the service, and in some instances satisfactorily to the owners. We have had two descriptions of steam vessels employed in the fishery; tho first, the old wooden sailing ships, which had been engaged in the service for some years, but which were afterwards fitted with screw machinery and auxiliary steam power. The second, iron built ordinary screw steam-vessels; but which proved, I believe, almost a total failure. The material of which they were built, and the want of strength for such a purpose, proving them altogether unfit to contend with the severity of the climate and rough encounters with the bergs and fields of ice, some becoming total wrecks, while others returned bruised andrent, and were with difficulty kept from sinking. A question here arises how far iron ships are calculated to bear the severe frosts of high latitudes, and whether wooden-built vessels, with all their defects, are not the best adapted for encountering such a climate? The screw steam-ship which was first sent from Hull, or any other place, to the fishery as an experiment, was the Diana, timber built, 353 tons and 40 horsepower, high pressure, the property of Messrs. Brown, Atkinson, nnd Co., of Hull. This vessel had been soino time engaged in the fishery as a sailing ship; but her spirited owners, thinking an important advantage could be gained, determined upon the adoption of steam power, and at once had tho Diana fitted for the spring of 1857 byMessrs. 0. and M. Earle, who put in the engines, and made the screw to lift out in case of need. The experiment fully answering their expectations, Messrs. Brown, Atkinson, and Co., bought the Chase, a tine American built ship of immense strength, nnd of 5J8 tons. She was fitted by Messrs. Martin, Samuelson, and Co., with condensing engines of SO-horse power, and despatched

• British Association, 1859.

to the fishery in the early part of 185S, nnd with good results. By the application of steam, ships in this service can now make a voyage first to Greenland, and afterwards to the Davis Straits. In tho commencement of this year several ordinary iron screw steamers were despatched to Greenland, viz., the Corkscrew, Gertrude, Einmeline, and Labuan, the latter only of this class, which is the property of Messrs. Bailey ami Leetham, had any success; but in conseqnenc other great strength and peculiar form, succeeded in a tolerable way; the others were much damaged, and, as I have already remarked, returned in bad condition. The Labuan is 581 tons burthen and 40-horso power.

The next point of interest connected with the steamships of the port of Hull refers to alterations made ill some of the vessels. The Emerald Isle, a piddle timber-built ship of 1835, the property of Messrs. Geo and Co., originally 135t.j long, lengthened 35 ft., with a gain of 11 in. draught of water, and an increased capacity for 100 tons dead weight. The Sultana, iron screw steamship of 1855, the property of tho same house, originally 150 ft. long, lengthened SO ft. with a gain of 10 in. draught of water, and an increased capacity of about 100 tons. It is interesting to observe that in both cases we have no diminution of speed through the water, and that both vessels are improved as sea-boats. Daily experience teaches tho advantage gained, in almost every point of view, by ships of great comparative length. The iron steamship Lion, of Hull, formerly a paddle-boat 219 ft. long, but now converted into a screw steamer by her owners, Messrs. Brownlow, Lumsden, and Co., under the direction of Mr. Anderson, their engineer, exhibits the great advantago gained by the alteration. Her register tonnage is 090, and the total tonnage 1,014. She was formerly fitted with steeple engines of 350-horso power, and had four boilers, two before and two abaft the engines; but these were subtituted for direct action engines of 150-horse power, and two of her old boilers replaced, and by this alteration a clear length of hold in midships of 23 ft. is gained. She required before the conversion 650 tons of coal for a Petersburg voyage, and consumed 30 cwt. to 40 cwt. per hour; but uow 350 tons for the voyage, and a consumption o^iO cwt. per hour. By the chajgc of machinery uhout 130 tons of dead weight is removed from the ship, and she is now able to carry 400 tons more cargo. Her speed is also improved considerably; beforo the alteration, when drawing on an average lift., the rate was six knots and a-half, but since tho change, when drawing even more water, they can steam eight knots. Thus throughout a saving almost in all the departments of the ship, and other advantages, have been effected in this important change. During the last two years manyfine steamships have been built in Hull, and others are in process of building for English and foreign servico by Messrs Brownlow, Lumsden, and Co.; Messrs. C. and W. Earie, and Messrs. Martin, Samuelson, and Co. The last-named firm aro making rapid progress in the building of two large paddle steamships for the Atlantic Royal Mail Steam Navigation Company of the following dimensions, power, &c.:—

Feet.
Length between tho perpendiculars ... 3B0

Beam moulded 40

Depth ... 30

Tonnage, builder's measure 2,809

Nominal horse-power 800

These ships aro to have three decks, and to be fitted fore and aft for passengers. Speed through the water, twenty miles per hour. They will bo of immense strength, and their build and form such as to ensure their becoming fine sea-boats.

Since the meeting of the British Association, at Dublin, considerable advance has been made in London and other ports in the application of superheated steam, and, I believe, with great success and satisfaction in the results; Hull, howeviT, before taking a decided step in this important discovery is anxious to see and adopt the best mode of tho application of the principle, being assmed

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