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"The decime has never succeeded in supplanting the sous in retail transactions, although for all important calculations the franc and centime notation has become universal." Report, p. 9.

At New York the price of a bottle of beer was called three shillings, although it was inserted in the bill as 37 cents: and generally throughout America although prices are expressed in cents, the number of cents employed shows that coins are still in use that do not belong to the decimal system. Kelland, Report, p. 13.

I assume, however, that the introduction of a good coinage of account is complete, when its notation is used "for all important calculations" and for lists of prices and tavern bills; although the word sous may still be used for five cents, and the confusions of American coinage may not entirely disappear for ages; and that as decimal coinage does in fact make its way steadily and without recoil, its ultimate adoption is certain, although that adoption may never put out of use such words as sous and shilling.

If the object were simply to obtain a good chandlers' coinage, it would be necessary to consider whether it would do to leave the cent to be subdivided into binary fractions, to which it would have, in the opinion of the commissioners, a natural tendency (Report, p, 10); there are, however, the difficulties of transition to be surmounted, and to meet these I think that

The penny must be retained.

I propose, then, to coin a mite in value 3th of a penny, and as the cent would contain 12 mites, the coins of account and the chandlers' coins would be connected, and every existing coin could be retained excepting the halfpenny and the farthing and even these would be current when they made up pence.

It has been objected to the £ and cent as coins of account, that the cent is too large for a minimum. Bankers at present use a penny, and Professor Kelland says, Report, p. 28:-"It is only by the universal consent of their customers that they are now able to neglect sums less than a penny, not merely in the totals of their accounts, but in every single bill of exchange or other separate item. It is impossible to guess when a similar agreement would be come to with reference to a new minimum."

I believe that this is erroneous, and that a banker consents to borrow the money, and to transact the business of his customer, on the condition that he shall not be troubled with small fractions, and whether 1 or 5 cents became the minimum would be decided by bankers themselves.

The minimum chandlers' coin would be the mite, and it would, as far as magnitude is concerned, be neither better nor worse than the farthing; it would divide the penny by 5 only, but the cent by 2, 3, 4, 6; and, therefore, unless the value of this property has been overrated, it would be a better chandlers' coin than the farthing.

A half cent would, I think, be an essential coin. The coinage would then stand :

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The fourpence, the threepence, and the sixpence should be allowed to disappear as soon as convenient, and ultimately the peany also; leaving the decimal scale composed of

£, florin, shilling, cent, and half-cent; to which the chandlers' scale would only add the mite. The mite is used, principally, as a coin of transition; it enables the penny to exist in conjunction with the decimal coins. The additional experience which the use of these coins afforded would decide whether the mite should be permanently retained. When it had discharged its function of introducing the cent without disturbance to existing habits, it might be withdrawn, and the mil substituted; a complete decimal system would thus be obtained.

To recapitulate: I propose that a cent and a mite be coined forthwith, and that public accounts be henceforth kept in the £ and cent. That as soon as expedient a half-cent stamp be substituted for the penny one.

No coin need be actually withdrawn, but the farthing, halfpenny threepenny, fourpenny, and sixpenny should disappear as soon as convenient; and there should be no new issue of the penny.

To make a bronze cent of a convenient size would be a problem worth the best attention of the metallurgist; a silver cent would for size be neither more nor less convenient than a threepenny piece.

The extension of the common numerical scale to weights and measures will result from the operation of the causes which lead to its adoption in the monetary system, but will not be a consequence of that adoption, nor necessarily connected with it.

The Report truly states that the weight of scientific authority is in favour of the projected change in the coinage. It is undervaluing the authority of one of those who favour the change to call it simply scientific; the rare power of estimating the wants of non-scientific minds and of bringing the truths of science within their reach, gives to the opinion of one who so eminently possesses it a weight incomparably above that of mere scientific authority.

The Report states also that there is an indifference to the change among commercial classes; the change appeals to the reason and the judgment, and will, therefore, never enlist enthusiasm in its favour. Commercial men have moreover the habit of using the present system, or they employ those who have; there is nothing to force on their attention the advantages of a simpler one.

Give the value of x+x+x+x4 when x=114d., and find the square of £19 19s. 11 d., are to be found among educational questions propounded during the present century; and they might be restored to their place as such without exciting indignation at Lloyd's.

There is, however, a class neither scientific nor commercial; it consists of men whose education gives them a clear conception of the advantages of the decimal system; and one of this class who has not the mechanical skill which a commercial clerk can acquire, nor the trick of memory which a calculating prodigy possesses, winds through the clumsy complication of a colmun marked £ s. d. with a feeling that the occupation is a degrading

one.

The coinages with which the issue of the cent would establish a community appear to be those of Venetian Lombardy, Austria, Holland, Prussia, and France, the franc being, very nearly, four I am, Sir,

cents.

Your most obedient and most humble servant, JOHN TOZER.

3 Inner Temple-lane, 18th Oct., 1859.

A letter from Alexandria says:-The laying down of the electric telegraph between Suez and Aden has, in spite of bad weather, been accomplished by the Cyclops. From Aden the electric wires are to be carried to Schugra, then through Hadramant, a pro

vince of Southern Arabia, then to the isle of Socotora, at 250 miles from the Straits of Babel Mandeb, and then by the isle of Ceylon and the Gulf of Bengal to Calcutta. When the line shall become completed, the total length of cable submerged will be 3,750 miles.

UNSINKABLE SHIPS.

TO THE EDITORS OF THE MECHANICS' MAGAZINE." Woolwich Dockyard, 8th November, 1859. GENTLEMEN,-My letter on unsinkable ships in the Society of Arts' Journal of the 28th ult., and your editorial article thereon in your last week's number (No. 45), have already attracted the attention of inventors with a view to the production of materials suitable for the purpose to which I have alluded, viz., the construction of unsinkable ships; and from the nature of the communications which I have received you will do me a favour, and some of your inventive readers a service, by inserting in your Magazine my letter of the 11th ult. in full as it appeared in the Society of Arts' Journal, excepting that I will thank you to place the two extracts from the Times in juxtaposition. There is no part of your editorial critique to which I object, although evidently intended to overrule my suggestion. The great use of publicity is to draw the attention of thinking men to the subject that may be referred to, and as all your readers are of a class who think for themselves, I am satisfied that only good can result from any latitude of expression or forced construction of my views on which, as in some respects in this case, you may be enabled to advance some sound and useful views of your own. practicability of the principle of my suggestion, namely, that ships may be made unsinkable, however perforated by shot, will, I have no doubt, be conceded; but the extent to which the adoption of this principle can be advantageously carried will greatly depend on the properties of the material that may be brought forward, including the few properties that I have enumerated to exemplify my views, and many others, such, for example, as being fire-proof, which it is hoped may be effected now that many preparations have been devised for rendering even wood uninflammable. The comparative expense of such unsinkable ships with reference to any other known mode of preventing accidental foundering, and setting Armstrong's ordnance and, I may add, the contemplated Nasmyth steam ram, at defiance so far as the absolute sinking of such ships is concerned, is essentially dependent on the success that may attend the inquiries now proposed to be set on foot, combined with the plans that may be devised for the application of such material to the construction of floating bodies, whether intended for the purposes of commerce or

of war.

The

And here again, as you truly, though rather sarcastically, observe, is a subject for the exercise of inventors "worth a very handsome premium, and the Society of Arts would do well to offer one for it before they offer the other."

I

concur in this your recommendation to the Council of the Society of Arts, only I would prefer that the required material possessing in the highest degree the properties of specific lightness, toughness, non-absorption of water, cheapness, uninflammability, &c., &c., &c., be determined upon before the premium for its application to the purposes of naval architecture be offered; also, as another preparatory step, I would suggest for consideration this question-Where is this premium to come from? On which point I may observe, that if improvement in modern ordnance neces sitated the introduction of iron-cased ships of war such as the Trusty, and if further improvements, such as the Armstrong gun, firing elongated bolts of malleable iron or steel, has already rendered iron-cased ships of the Trusty class no longer trustworthy, but necessitated further improvement in the hope of defying even the Armstrong system of ordnance; as, moreover, the steam ram is looming in the distance, and as it is difficult to see any end to this rivaly of gunnery and rams versus iron-cased ships, or of the cost that it will involve, I would merely suggest that if for every one million of money thus devoted by Parliament to the construction of iron-cased shipping with a view to invulnerability, £100 only were awarded as a premium to naval architecture, with a view to promoting the efficiency of unsinkable ships of all classes respectively, it is probable that such rivalry between modern intellect and

trial. I found Admiral the Earl of Dundonald at

quantity. Equally irrelevant to the commercial
excellence of the vessel is the point of recoaling
only at the end of the voyage. That solely con
cerns the commercial management, and though
put forward as a desideratum, will, I hope, be
found otherwise, through a more valuable freight
than coal being secured.

modern ordnance would be conducive to public |
good and to the peace of the world. For
my part I would have little doubt of Britain being
at peace with all the world if all ships were
effective for their respective uses and unsinkable.
Pertinent to this subject it may not be out of
place that I here refer to a noble sentiment of
Admiral the Earl of Dundonald. It was my official
The point, then, exclusively for discussion is
duty in January, 1818, to test the performance of that which Mr. Atherton says is the subject of
the Banshee, a vessel built by Government ex-
his Table No. 2, "showing the superior capability
pressly for the service. On my return from the of large ships, as indicated by the progresively
reduced ratio of power to a progressively in
Woolwich Dockyard; I told him of the unprece-creased displacement, the speed being constant,"
dented steaming speed we had attained, namely, and requiring for decision the horse power as de
16 knots per hour. The noble Admiral replied: clared by the indicator. In what degree this
"Had the command of such a ship in war, I superiority belongs to the Great Eastern will be
would not encumber myself with guns-I would satisfactorily determined only when she is deeper
run up to and board everything I could catch." in the water than at present, until which time it
Various essentials to the realisation of this noble will perhaps be better to wait; but it is clear
sentiment, so characteristic of the man, are ob- from the very nature of the subject, and from
vions; an unsinkable ship with machinery invul- these Mr. Atherton's own views of it, that her
nerably cased in, the crew protected from the merits must necessarily be equally pre-eminent
with her size, unless there is some awkward cir-
enmstance in her build sufficient to neutralise all
advantages. Her lines are admitted to be good,
but Mr. Atherton thinks unfavourably of her
small draught in proportion to breadth. I confess
it is so much a question of compromise to be dealt
my incompetency to give an opinion on this point,
with by the practical man alone, but I must say I
should be surprised if it were proved that any
thing in this circumstance adverse to her perform
ance is not fully compensated by her small breadth
in proportion to length, thus having the balance
due to capacity untouched. I think, indeed, it
would be surprising if it were not far more than
compensated, when the great depth to which
otherwise she would have been immersed is con-
sidered, and the great resistance opposed to the
translation of water at such a depth. Mr. Atherton
brings down the performance of the Great Eastern
to the rather low co-efficient 200, but then he gets
at the horse-power, not by means of the indicator,
but through the consumption of coals, which is
unfair to the ship. Besides, the datum of 34 lbs.
per indicated horse-power per hour is only a loose

Minié, and commanded by a Dundonald (and a
thousand such men will be forthcoming when
required), would be an ugly customer, I guess.
But it is not my purpose at present to go into any

details of naval architectural construction in con-
nection with unsinkable ships.
observe that the property of being unsinkable does
I will merely
not necessarily imply that such vessels shall have
no stowage below the level of the load water line
which may be appropriated to machinery; and I
may further remark that, by the construction of
line-of-battle ships, such as the Royal Albert,
only about one-third of the internal cubical capa-
city of the ship is below the level of the load

water line.

In the conclusion of your critique you respectfully invite me to tell you what I am thinking of, and I as respectfully reply that since the introduction of iron cased ships, and especially since the reported practice on the Trusty, I have been occasionally thinking how ships of all classes respectively may be rendered unsinkable compatibly with the respective uses for which they may be designed; and this is the subject on which I now hope to interest the Council of the Society

estimate.

of Arts, and through them, and by the aid of the
Society of Arts' Journal, and with the co-opera-radical

tion of the MECHANICS' MAGAZINE and other

publications usefully devoted to such inquiries, I hope to interest the public. I am, Gentlemen, Yours very obediently,

CHARLES ATHERTON.

THE GREAT EASTERN AND STEAM SHIP

ECONOMY.

TO THE EDITORS OF THE "MECHANICS' MAGAZINE."
GENTLEMEN,-Mr. Atherton has been so oblig-
ing as to favour us with his views on the above
subject in reference to some remarks of my own,
and he includes a slight notice of the doubt I ex-
pressed in my last communication, as to the appro-
V3 D3
priateness of the formula
for determin-
Ind. h. p.
ing the dynamic performances of the Great
Eastern and of the mercantile marine generally.
In order to come to a clear understanding on the
suitable application of formula to this vessel, we
must divest the subject of some extraneous conside
rations to which Mr. Atherton has adverted,
although proper enough in their place.

should fix on the mathematical mind the work done in the water, and not technically the corresponding property of the ship. It is true we cannot apportion the work between the useful and the useless, or express either in terms of force and motion; but the useful effect is sufficiently tangible to be measured in a way to serve the purpose of comparison, and therefore cubic feet would stand as well as tons for the displacement. It is of course necessary that the cube of

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the velocity should be taken; but what does the power of the displacement mean? We see that looking at the physics of the subject in the water, we must either take this factor as it is, or discard it altogether, and accept the midship section instead thereof. Perhaps, however, it means this, that it does duty for the midship section-a false fictitious thing instead of the real. In that case, perfect or imperfect, we wander from the effect to the means; we lose sight of burthen altogether, and velocity alone coines to be considered as the useful effect. This limitation is indeed very desirable when we wish to take the comparative worth of the lines simply of different vessels, and the corresponding formula is very appropriate for the Royal Navy, or for mere passenger vessels. But a factor avowedly standing virtually representing it, and labelled otherwise, is for the midship section is one thing, and a factor another thing with another character. The forhonest face; it talks of tonnage and displacement, mula in which it stands does not present an and makes believe to be a true servitor of solid commercial interests, but under the guise of their own livery, slips away from his charge to run after other masters of the skip-jack race, serving them, by the bye, in the most slovenly manner

withal.

but without any allusion to Mr. Atherton, who, as I cannot in conclusion refrain from observingI understand, is not the author of this objectionextent the animadversions I have often committe able formula-that it certainly justifies to its own to your pages, concerning the frequent deficiency in mixed mathematics of a clear and sound un derstanding of the physics involved in the subject investigated, by which pompous nothings are enabled to gain, through a mathematical dress, a prestige which they do not deserve.

I

Yours, &c., BENJAMIN CHEVERTON.

THE INVENTION OF THE SCREW
PROPELLER.

TO THE EDITORS OF THE "MECHANICS' MAGAZINE."
GENTLEMEN,-Having read in your last week's
paper a very interesting account of the invention
of a screw propeller by George Blencowe, which
think may not improbably have been the real
origin of the one now in general use, I venture to
send you a short notice of another inventor,
whose discoveries were made a little earlier in
time, but were not successful in obtaining any
public recognition after their first trial.

It was, however, to what I conceive to be a fault in the formula used by Mr. Atherton, that I wished to draw his attentionwhether my proposed correction told favourably or otherwise on the merits of the Great Eastern. Am I to understand that he maintains the appropriateness of that formula, or even indeed its correctness, relatively to its ostensible purpose? or will he acknowledge with me, that the simple displacement would be a better factor than any power thereof? It would in this form be a much more satisfactory criterion of the merits of a ship, in the matter of size and build purely as a scientific construction for a mercantile purpose, and yet for a criterion of practical commercial excellence it would be nearer the truth to take the actual weight of the cargo, by which any Between the years 1821 and 1828, Mr. James peculiarities of construction, such as cellular Wilson, of Patricoft (subsequently acting-manager sides and the like, would be eliminated. respect to the formula as it at present stands, will with a view to the construction of a screw proBut in to Mr. Nasmyth) inade numerous experiments any one speak up for it? In addition to what I peller for ocean navigation. have already said, let me ask-what is it that is he completed a small model (fitted with both After many trials, intended to be expressed? Is it not the power on paddle and screw-propellers), which was tried with entire effect was what is referred to, these quan- of Mr. Hunter, of Thurston, and other gentlemen But if the perfect success at Leith in 1828, in the presence tities would be always equal to each other. It is well versed in mechanical pursuits. The result the useful effect, then, that is meant, and this being divided by the power, gives us the compara- Edinburgh for a more complete series of experi a request from the Highland Society of of a small sum of money from the Society in aid ments on a larger scale, together with the grant ments were made on March 10, 1828, and subs of Mr. Wilson's undertaking. The first experiquently in April of the same year, and a full report published on May 4th, 1828, by the sub-committee appointed by the Society to witness them, in which it is stated that a boat eighteen fet long had been constructed, and fully tried in the open sea outside the pier at Leith, in a very heavy sea and a stiff N.N.E. breeze, in the presence of Admiral Sir David Milne, Captains Boswell and

one side and the effect on the other?

Now, it is the performance of the Great Eastern as a ship, in the two aspects of velocity alone and conjointly with burthen, and as being the tive worth of our contrivances for utilizing it as result of a definite amount of indicated horse- much as we can. Now, what is the useful effect in power, that we have to investigate, and not any the present case? It consists in opening out a merit in the engines and boilers. It is with the passare in the water; its positive value depending scientific application of the power as provided, and both on the extent and the velocity with which it not with any development thereof, that we have is effected, and its comparative value in the to do. The formula. must therefore be dividing and translating of the water, with the Wt. of coal. least possible velocity given to the least possible put aside as irrelevant, however useful in other number of its particles. Well, then, what need respects. I must, however, remark by the way, we else for the factors that are to express the that it will ever be vitiated by the factor D3, if useful effect, but the quantities that constitute it that factor be, as I apprehend, a misleading-velocity and displacement? The latter term

V3 D

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Trotter, R.N., and others, and that in the opinion of these gentlemen it had proved entirely successful, the impetus communicated by the propellers at the stern having been much greater than that which could have been given by oars, while the resistance offered to heavy seas on the boat's quarter was also much less.

The model made by Mr. Wilson was deposited in the rooms of the Highland Society, and was destroyed by fire a few years ago when their museum was burnt. Another, but I believe smaller one, is still preserved at Thurston House, near Dunbar, where it has remained for more than thirty years since the late Mr. Hunter first encouraged Mr. Wilson to proceed with his experiments. I believe that Mr. Wilson is about to publish a detailed account of his plans, from which it will clearly appear to what extent he is entitled to claim the invention of the screw propeller. I am, Gentlemen,

Your obedient servant,
W. S. W. VAUX.

British Museum, November 7, 1859.

RICHARDSON AND JAFFREY'S IM

a skeleton figure of the predetermined shape. This framing is then covered with sheets of cast or wrought-iron, which are riveted or otherwise secured to the internal framing. "The height and size of these towers must depend," say the patentees, "to a great extent upon the depth of water and the position of the work; we may, however, give as an example of a useful size for these towers diameter at the base thirty-five feet, tapering to a diameter of twenty-seven feet at the upper part. The open bottom towers constructed in this manner are taken out to sea in succession upon a powerful derrick or pontoon, or other suitable floating apparatus, and are then sunk upon the spot required; the towers are arranged in a straight or curved line at such a distance apart as to leave between each an intermediate space equal at the upper part to the smaller diameter of the tower or thereabouts. The towers being disposed in this manner, the water contained within each is then pumped out, and the interior of the tower is filled in with masonry, the blocks of stone being previously cut to the required shape on shore; in this manner the work may be carried on with great rapidity, the cement used in the building operations being PROVED BREAKWATERS. meanwhile wholly protected from the wash of the MESSRS. THOMAS RICHARDSON and G. W. Jaf- sea water. Instead of using stone as the material frey, engineers, Durham, have just completed a for filling in the towers, concrete, beton, or other patent for an invention which relates to the hard drying plastic cement may be moulded into arrangement and construction of defensive and blocks of the required figure on shore and dried; protective sea works of various kinds, such as these blocks when fitted into their proper places harbours of refuge, breakwaters, sea-walls, barriers, within the tower are to be cemented together and other sea-board structures or contrivances in- with a thin mixture of the cement or plastic matended either for the defence of the coast against teriel used for moulding the blocks. In some cases the action of the wind and waves or for protecting we should give the preference to another mode of shipping. Fig. 1 of the annexed engravings re-procedure, namely, to fill the whole of the inpresents in side elevation and partial vertical terior of each tower with beton' or hydraulic section a breakwater constructed according to this cement, as shown at B, which cement solidifying invention, and Fig. 2 is a corresponding plan and within the tower, the whole forms a compact and horizontal section of the same. In carrying out solid mass capable of withstanding the waves of the invention in the arrangement and construction the sea after the removal or wearing away of the of a harbour of refuge for ships the patentees, in external plates of metal. In lieu of this solid the first place, construct a number or series of mass of beton, a filling-in may be used composed iron towers 4 A, so that when these towers of beton, having a central mass or core of slag as are deposited in the sea at the predetermined at C, the interstices of which may be filled up with distance asunder, they extend outwards and par- the liquid, so as to form the whole into a solid tially enclose the required extent of sea room. mass. The operation of filling up the towers The towers are by preference made of a cir- with masonry or with plastic materials is matecular figure in transverse section, wide at the rially facilitated by the convenience which the base and tapering towards the upper part, sweep- summits of the towers afford for at once laying ing inwards from the base with a curve, or rising down a permanent gangway or road D from one upwards with straight sides of a gradually tapering tower to another, along which gangway materials or conical figure. These towers are by preference and implements can be conveyed with nearly the constructed of cast-iron or malleable iron, or same facility as on shore. In this manner the partly of both kinds of metal, but in lieu of these expensive and costly plant required in harbour and materials they may be constructed of stone or coast works of the ordinary kind are wholly distimber, and made solid in the manner hereinafter pensed with, and the work is done at far less cost described. In constructing the towers of metal a than can be accomplished with the usual strucframing of perpendicular and transverse circular tures. In place of constructing the towers of or cylindrical ribs is bolted together so as to form iron, they may be built wholly of stone, a suitable

caisson being sunk over the spot where the tower is to be erected; the water having been pumped out of the caisson, the work may be carried on with great rapidity if the several blocks of stone have been previously cut to the required shape on shore. The open spaces between the contiguous towers are filled in with open vertical frames E E, which serve to break up and divide the waves as they roll in, the water passing through the open screens without hindrance, and yet in a comparatively smooth and untroubled state, and so as to render the position of the shipping in the harbour perfectly secure. These lattice screens are con structed of balks of timber strongly bolted together, open rectangular spaces being left between the contiguous vertical and transverse beams of timbers. These lattice screens are by preference constructed on shore, and in the opposite faces of such contiguous pair of towers, a deep vertical groove is formed, either by bolting pieces of angle iron to the face of the tower, or by casting the grooves in the plates of towers, or by securing pieces of timber thereto in a similar manner. These lattice screens are taken out in succession on the derrick, they are raised thereby to a suflicient height to admit of their being lowered down into the grooves made for their reception on the contiguous faces of the towers. Another mode of constructing these screens is to form them of cast-iron pipes or of malleable iron tubes. The vertical tubes are connected together so as to form a frame or lattice by means of transverse bars of metal at the upper and lower parts, and, if necessary, at intermediate distances. These screens are fitted into the adjacent grooves in the towers in the same manner as described in reference to those composed of timber. In addition to the protective action of these screens there is another and highly important advantage attend. ing the use of them in harbour and other similas sea works, which is, that from their open con struction they prevent the silting up or accumu lation of the sand inside the harbour, as the tide has free access and egress through the open screen. so that the original depth of water is maintained, and a prolific source of expense in the maintenancs of dredging apparatus is avoided. The construction of harbours, piers, or quays upon this plan admits of vessels approaching close up to the towers, thus avoiding the waste of room and inconvenience attending long sloping sea-walls of the ordinary construction. Even in situations where a rigid or impermeable sea wall would not be objectionable, our system offers considerable advantages in point of strength, economy of first cost, and facility of construction. In such situations the towers are constructed and disposed as hereinbefore described, but the intermediate spaces between the towers are filled in either with a wall of masonry as at FF, or are formed of blocks of beton' or concrete cemented together, and

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defended or not on the outer or seaward side by a lattice-work of timber or metal. For these structures the towers may either be the simple iron tower sunk into its proper place, or it may be partially or wholly filled up with masonry, 'beton,' or other suitable material. According to this system of constructing harbours, breakwaters, sea-walls, and other similar exposed works, it is impossible to carry out such works in a manner more economical, for if properly conducted no portion of the materials employed need be wasted, which is far from being the case in structures of the ordinary kind, however careful the contractors may be in the disposal of their materials."

CLARK'S APPARATUS FOR HEATING
FEED-WATER.

MR. DANIEL KINNEAR CLARK, the well-known writer on railway machinery, has patented for the above purpose an invention of which he gives the following description :

The invention consists in a simple and compact method of heating the feed-water of steam-boilers by the forcible and immediate intermixture of currents or jets of water and steam brought into direct contact and travelling together, as follows:One or more jets of steam are discharged freely and directly through a pipe or other passage or chamber of suitable form, into which also the water to be heated is delivered, and through which it is passed in conjunction with the steam; in this confined passage the steam, in virtue of its initial velocity, forcibly impinges upon, mixes with, and disperses the water, and is quickly condensed, and the water is proportionally raised in temperature by the heat of the condensed steam. When more than one jet of steam is used, the jets may be placed side by side, or they may be placed When the heating apparatus is above the level of the source of water supply, the water may be raised to it by pumps or other external means. The jet of steam is so adjusted 28 by suction to draw and conduct the water into and through the heating passage, thereby assisting and, if powerful enough, superseding the use of external means for lifting the water. The jet

in succession.

nozzle may be contracted at the orifice to sharpen the blast. The water may be delivered round or within the jet of steam, which in the latter case is annular, or there may be a series of jets in a circle.

The heated water passes freely from the apparatus, and may be either pumped directly into the boiler or reserved for use. A free vent is provided for uncondensed steam. The supply of steam may be taken from the boiler direct, or from the exhaust passages of steam engines connected therewith, whether condensing or non-condensing. For convenience the whole of the exhaust steam may be carried through the heating chamber, the surplus or uncondensed steam being passed on to the atmosphere or condenser, as the case may be.

The apparatus may be made with parts readily removeable and easily replaced for collecting deposits from impure water. The vent for steam may be closed, if desired. Air vessels may be applied where needed for equalizing the flow of water. The water may enter through the open end of the heating passage or through perforations; and the heating chamber may be formed with one or more contractions or strictures, so as to induce more intimate mixture of the water and steam, or with one or more bends or undulations.

The heating chamber or passage should be of sufficient length to effect the thorough heating of the water, but it may be supplemented where needed by one or more diaphragms placed within or beyond the passage, so as partly to baffle or divert the discharging currents of water and steam, and further to intermix them.

When the steam is delivered intermittently at considerable intervals into the heating chamber, as in the exhaustion of steam from an ordinary steam engine, the supply of the water to be heated may likewise be delivered intermittently, in order that cold water may not pass unheated through the heating chamber in the intervals of the discharges of steam. The intermittent supply of the water may be effected in a self-acting manner by the exhausting operation of the steam inducing a partial vacuum and a flow of water into the heating chamber through the water entrances, against which flap or other simple acting valves

|

may be placed, so as to open inwards when exhaustion is effected; or it may be effected by means of stop-cocks, or valves, or intermittent pumps, actuated by the engine. By means of valves, also placed at any convenient part of the delivery pipe or chamber, the supply-water may be sustained at the level to which it is elevated by the inducing action of the steam. The whole of the steam from donkey pumps used in feeding steam-boilers may be condensed in this manner. The apparatus may be protected by a jacketing of steam from the exhaust or otherwise, or by a coating of felt or other material, to increase its efficiency by the addition of heating surface, and to prevent loss of heat.

The annexed illustrations exhibit various forms of the apparatus. In the Figures generally, 4 is the heating chamber; B is the steam pipe, from which the steam for heating the feed-water is discharged; C is the pipe, conduit, or vessel which contains and conveys the water to be heated. The water enters the heating chamber through perforations or slots a, a, so as to meet and mix with the entering steam, and the heated water is discharged into the cistern D, from which it is drawn off by the pipe E to be pumped into the boiler. Any residual steam in the cistern D may escape through the waste pipe F.

In

In Fig. 1 the heating chamber is enclosed in the water conduit, and is surrounded by the water. The tight air space at the upper end of the conduit acts as an air vessel. The steam nozzle is fitted air-tight into the heating chamber, in order to prevent the suction of cold air into the chamber, and the loss of heat thereby, and to sustain the exhaustive action of the steam. Fig. 2 the heating chamber and water conduit are placed side by side, and united at the upper parts where the steam is admitted. In Fig. 3 the heating pipe and water pipe are enclosed within a chamber which contains the heated water. The cold water is discharged into an upper chamber, whence it proceeds to the heating pipe. In Fig. 4 there are three heating pipes and three steam nozzles, one to each pipe, enclosed within the water conduit. In Fig. 5 there are several steam nozzles placed in a circle, playing into an annular

heating chamber placed within the water chamber. The cold water enters the annular chamber from within and from without. In Fig. 6 the steam is admitted in several jets into the heating chamber, which in this case is plain. In Fig. 7 the cold water is admitted in one or more thin sheets into the heating chamber. Fig. 8 illustrates the adaptation of a ball-cock to the cold water supplypipe, to maintain the water at a constant level in the cold-water cistern, and is useful when the

water is supplied from above the level of the heating apparatus. Fig. 9 shows an application of the invention to a locomotive, in which the heating chamber is placed horizontally over the barrel of the boiler. One pump may be employed to supply the cold water, and the other pump to supply the heated water to the boiler. When the feed pump is not in action, the heated water flows freely back into the tank or tender. Figs. 10, 11, 12, 13, show various other forms of the apparatus. In Fig. 10 a core is introduced within the heating

THE STRENGTH OF WROUGHT IRON
AND STEEL.

THE following condensed abstract of a first set of experiments, made by Messrs. Robert Napier and Sons, on the strength of wrought-iron and steel, was communicated to the British Association at the Aberdeen meeting by Professor W. J. Macquorn Rankine, C.E., LL.D., &c. :-The experiments to which this abstract relates form the first set of a long series now in progress by Messrs. Robert Napier and Sons, the details being conducted by their assistant, Mr. Kirkaldy. The whole results are now in the course of being printed in extenso, for publication in the "Transactions of the Institution of Engineers in Scotland;" but some time must elapse before they can appear, owing to the great volume of the tables, and the number of particulars which they give.

The present abstract is all that it has been meeting of the British Association, and, notwithstanding its brevity and extreme condensation, it

Proceedings of Societies.

INSTITUTION OF MECHANICAL ENGINEERS.

THE general meeting of the members of this Institution was held on Wednesday, the 21 instant, at the house of the Institution, Newhall Street, Birmingham, Henry Maudslay, Esq., VicePresident, in the chair. The Secretary (Mr. W. P. Marshall) having read the minutes of the previous meeting, held in Leeds, the chairinan alluded to the irreparable loss that had been su4tained by the profession and the world at large in the recent lamented death of Mr. Robert Stephenson; and desired to express, on behalf of the meet

ing, their high appreciation of his great mechanical genius and their warm admiration of his many noble qualities. Mr. Stephenson had taken a strong interest in the development of the Institution in its earlier years, having succeeded in the Stephenson, their first president; and both had largely aided in promoting its welfare by their

chamber under the steam nozzle to diverge the found practicable to prepare in time for the presidency his father, the late Mr. George steam, and so to promote the mixture of the steam with the water. În Fig. 11 the steam is discharged from an annular orifice near to the circumference is believed that the results which it shows will be of the heating chamber. In Fig. 12, also, the steam is discharged from an annular orifice, and the water is introduced against the steam from within and from without the annular orifice.

In the illustrations it has not been thought necessary to show in detail any of the obvious and well-known modes of conveying steam to the heater, or of inserting linings or vessels for the collection and easy removal of deposits from imIt is obvious also, without further pure water. illustration, that by a suitable disposition of cocks or valves the apparatus may be turned off at any time and the engine maintained in working order.

STEAM NAVIGATION ON THE RIVER

AMAZON.

found of interest and importance. It gives the tenacity, and the ultimate extension, when on the point of being torn asunder, of the strongest and the weakest kinds of iron and steel from each of the districts mentioned. Each result is the mean of four experiments at least, and sometimes of many more.

The detailed tables, now being printed, will show many more particulars, and especially the contraction of the bars in transverse area along their length generally, owing to " drawing out," and the still greater contraction at the point of fracture. The experiments now complete were all made with loads applied gradually. Experiments on the effect of suddenly applied loads are in

progress.

TABLE A.-IRON BARS.

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Yorkshire strongest weakest. (forged) Staffordshire: strongest.

weakest

West of Scotland: strongest Sweden: strongest

weakest

Ultimate Tenacity in extension in lbs. per decimals sq. inch. of length.

0.256 0-205

62886

69075

65392

0.202

62231

0.222

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weakest Russia: strongest. weakest

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MR. LAIRD, of Birkenhead, has just completed a vessel for a company formed under the auspices of the Baron de Mana, of Rio Janeiro, for the navigation of the river Amazon. This vessel is named the Manàos, she is 255ft. long and 25ft. beam. Her tonnage, old measure, is 681, and she is intended to combine great carrying capacity with speed. She is arranged something on the plan of the American river boats, the decks being carried out to the extreme width of the paddleboxes, and the whole of the accommodation for first and second-class passengers is in large deck houses, leaving the holds entirely free for cargo and coals. Her engines, also constructed by Mr. Laird, are of 180-horse power nominal, but worked on the trial to between 950 and 1,000 indicated horse-power. The paddle-wheels are on the feathering plan, and the boilers are fitted with superheating apparatus, and other modern improvements. In order to test this vessel's capa bilities for speed and seagoing qualities, she was despatched from Liverpool to Beaumaris on Monday last, and made the passage from the Rock Light (a distance of 48 statute miles) in three hours, giving an average speed of 16 miles per hour. She returned from Beaumaris to Liverpool on Wednesday in 2h. 60min., being an average speed of 17 miles per hour. The Manàos was partially loaded, and had on board two large iron respectively the strongest and weakest crosswise. barges shipped in pieces, to be riveted together on arrival at Para, besides a considerable quantity of coal. The distance between Liverpool and Beaumaris has never been accomplished in so short a time before. The vessel and machinery have been constructed, and the above trial of speed made, under the superintendence of Commodiore Hoffsmith, a distinguished officer of the Brazilian navy, who was sent over by the company for that purpose, and also to superintend another vessel now being constructed by Mr. Laird for the same owners.-Times.

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0.076

0.951 0.108 0.153

0-0571 0-1986 0-0064 0.1964

NOTE. The strongest and weakest lengthwise are also

COINING BY CONTRACT.

TO THE EDITORS OF THE MECHANICS' MAGAZINE." tract" in your last week's impression, you assume GENTLEMEN,-In the article "Coining by Conthat we have obtained a promise of contract for the proposed new bronze coinage.

promise, either directly or indirectly, and that we We beg to state that we have received no such are not in any way responsible for the paragraph in the Manchester Guardian, from which the

inference has been drawn.

Your obedient servants,

RALPH HEATON AND SONS.

Birmingham, November 7th, 1859.

counsel and assistance. A considerable number of new members were elected; and the presideat, vice-presidents, and members of council were nominated for the next annual election.

The first paper read was a "DESCRIPTION of OATES'S BRICK-MAKING MACHINE," by MR. Jous which is the invention of Mr. J. P. Oates, of E. CLIFT, of Birmingham. In this machine, Erdington, near Birmingham, the bricks are made direct from the clay, without previons crushing rollers when containing a mixture of preparation beyond passing through the ordinary

vertical screw with a large flat blade, widened stones. The machine consists of a revolving conically at the upper part, and working freely within a cylinder, at the bottom of which is the mould block, sliding horizontally, containing two moulds in which the bricks are formed. The upper part of the cylinder is expanded to form a hopper, into which the clay is supplied, and is then drawi down into the cylinder by the revolution of the screw and pressed into the mould below. The mould thus filled is then withdrawn horizontally, and the other empty mould brought under the screw to be filled with clay; and the first brick is discharged from the mould by a vertical piston pushing it through the open bottom of the mould on to an endless band, by which it is conveyed to the front of the machine ready to be removed direct to the kiln for burning. The clay is supplied continuously by the action of the screw; and, at the instant when the bottom of the clay cylinder is closed by the change of moulds, an outlet for the clay is provided by means of a horizontal escape pipe, opening from the bottom of the clay cylinder, and acting as a safety valve to prevent any excess of pressure in the machine or any risk of overstraining. The outer end of this escape pipe is open, and the friction of the clay against its sides determines the limit of pressure in the machine the clay is pushed forward in the pipe or an inch each time the brick moulds are changed, The bricks are completed at a regular rate of 12,000 per day in ordinary work, or an average of twenty good bricks per minute; and the machine is capable of making as many as thirty bricks per minute. Several of these machines are at work in the neighbourhood of Birmingham and elsewhere, some of which have been working regularly for three years. The crushing strength of the bricks has been found to double that of hand-made bricks of the same district; and their transverse strength is also considerably greater than that of hand-made bricks. No difficulty is experienced from the bricks not having been dried before stacking in the kiln for burning, as they are sufficiently dry on leaving the machine; so that bricks previous to burning is dispensed with. A the process of drying required for hand-made number of samples of the ordinary bricks made by the machine were exhibited, and specimens made from different qualities of clay in different parts of the country; also a working model of the pressing screw and escape pipe of the machine, showing the

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