THE

MECHANICS' MAGAZINE.

LONDON, FRIDAY, JANUARY 7, 1859.

of the earth in that country. Mr. RAE, "a
Glasgowegian," pronounces them to be good,
and promising better, as they are got from
the surface, on the bank of the Muatoze,
where they have been exposed to the action of
the floods and atmosphere for ages. There is
an immense coal-field there, and many of the
seams crop out. With coal, and the best iron
ore in abundance, surely Africa will not always
be the trodden-down nation it has been. Their
vessel was the first that ever steamed to Tete,
and was visited as if it had been another Levi-
athan. "It is sad to see so fine a country,"
says the estimable Doctor, "in this state. We
meet some very fine cotton, growing wild,
wherever it has once been sown. It is long in
the staple, and has been introduced, as its name
imports. The other has a short strong staple
which clings to the seed, and is more like wool
in the hand than cotton. We have also more
lignum vitæ than ebony. My men were
still at Tete, though 30 of them had died of
smallpox, and six had been killed by a neigh-
bouring chief. The poor fellows received me
with great joy, and no less glad was I to see
them. All the party is now well. We have
had illness, but no coast fever. I think as both
we and the Pearl escaped, it was greatly owing
to pushing with all our vigour away from the
mangrove swamps at the mouth of the river.
These are the hotbeds of fever."

.

PHOTOGRAPHIC DRAWING ON WOOD, for the

THE SHIPPING STATISTICS AND TONNAGE QUESTION is again revived in our columns this week, by the publication of the Report of the British Association's Committee. The same question also recurs in a correspondence pubWHILE all the world is keeping holiday, and lishing in the Society of Arts' Journal. *Mr. MACGREGOR, of the Temple, there opens the London is lying "unseen, yet sounding through subject in a letter on Mr. REED's paper on the its shrouding mists," we shall prefer occupying Ships of the Royal Navy. Mr. MACGREGOR our opening columns this week with a few parastates that, having seen the Turkish ships at graphs on matters of general interest, rather Sinope before the battle, and other avowedly than with formal articles of a more technical large ships in America, he has found that Turks, and troublesome character. And, first, a word Americans, and Russians, all exaggerate the or two to our subscribers. We have received sizes of their vessels when it suits their purseveral requests to publish a weekly table of poses; and he says, "it is extraordinary that contents, and also to discontinue numbering the men will continue to compare the tonnage of advertisement pages with the others. To both vessels, as if a proper standard were actually in of these requests we have cheerfully acceded, use." Mr. REED, in reply, admits the imperas our readers will observe. We shall take care fection of the existing rules for calculating at the end of the first volume, so to number the tonnage, but contends that they form the best index, or some other introductory matter, as to basis of comparison which we at present have, supply pages 1 to 4, of which, when the adverand shows that he carefully bore in mind the tisement sheets of last week's number are discrepancy between the English and American removed, the volume would otherwise be rules in making the comparison between the deficient. The first volume will thus be made Shannon and the Merrimac the only comparison complete, and consecutively paged throughout, instituted by him. He adds that the tonnage as our correspondents desire. We have to question has lately had such a mountain of apologise for the lateness of our last week's words heaped upon it that he made no attempt issue, for the somewhat unfinished appearance to exhume it before the members of the Society of a portion of our impression, and for the of Arts. The report referred to will come scarcity of our Abridged Specifications of under our consideration in due course. Patents. All these things were contingent upon PREMIUMS FOR INVENTIONS are again offered the first appearance of the Magazine in its new purposes of the wood engraver, has this week by the Council of the Society of Arts, and form, and will not, we confidently believe, occur been most satisfactorily advanced. A conver-gentlemen having a love of distinction, gold and again. In respect to the Abridged Specifica-sation with Mr. CROOKES-whose name is well- silver medals, and pounds sterling, will do well tions, we wish it to be understood that we shall known among photographers, and who has to apply to the Secretary for a list of subjects soon bring them up to date,and then publish recently become the editor of the best of all for improvements in which prizes will be them regularly, week by week. photographic journals (the Photographic News) awarded. Under the will of Dr. SWINEY, & prepared us some months since for the re-silver goblet, worth £100 sterling, containing ception of the improvements which are now gold coin to the same amount, will be presented made public by that gentleman. He covers the on the 20th of January next to the author of wood block with oxalate of silver and water, the best published treatise on Jurisprudence. to which a little gum or pulverised bath-brick A special gold medal, provided by the gift of may be added if desired. The material is spread Benjamin OLIVEIRA, Esq., is also to be given over the wood in the same manner as the for a substitute for cotton; and other special engraver's ordinary flake-white and gum-water gold and silver medals for an incombustible are applied, a delicate and almost impalpable paper, and a design for a Literary and Scientific coating of the oxalate being thus produced. Institute. An abundance of the society's ordiThe block may then be placed in a drawer, or nary gold and silver medals is also ready to be in any place from which daylight is excluded, scattered among men possessing either genius and there left to dry, or until required for use. or ingenuity. They may patent their inventions When taken out and exposed to sunlight under and still win the prizes. Let inventive brains a negative in the printing frame, a positive and diligent hands become busy! picture will be produced upon the block, as it THE NAVIES OF ENGLAND AND FRANCE form is upon paper in the ordinary way. A block the subject of a lengthy paper transferred to thus prepared is ready, without any further pro- the Times from a Gerinan publication entitled cess, for the engraver's hands. In cutting it, the "Conversations Lexicon," published at he need only be careful not to expose it to the Leipzig. The most remarkable feature in this direct rays of the sun; diffused daylight will paper is the prominent notice it takes of the not blacken it, except by many hours of ex-modern expansion which the French navy has posure. By this process all kinds of pictures undergone. In this respect it has a decided may be transferred to the wood block; and the value, and deserves the attention of the English inventor sees no reason why it may not be people. It is written, however, with undue applied to the reproduction of stereoscopic partiality; is in many places very erroneous, views, which would bring them within reach of and owes its position in the leading journal to the humblest. A use which is more important its undue depreciation of our present navy, the to us is that of applying reduced mechanical nature and strength of which its author but drawings, and photographs of machines them- imperfectly comprehends. This we shall proselves, directly to the wood. This would save bably show in an early number. much time, and, in the main, conduce to greater accuracy than is usually attained at present. These applications must, however, be made with care, for there is sometimes a disposition, either in the sun, or in the chemicals, or in the manipulator, to introduce twists and turns which, in portraits at least, we know not always how to tolerate. We remember that DE QUINCEY once complained of the excessive proportions which his mouth, and most other mouths, acquired whenever the sun painted the picture; and there are many parts of machinery which will bear distortion even less than Mr. DE QUINCEY's features.

DR. LIVINGSTONE sends us news from Tete, on the Zambesi. He has been much hampered by the great draught of water of the Pearl, which, it will be recollected, was appointed to see him fairly, and as far as possible, on his expedition. He adheres to the opinion he has all along expressed that a vessel drawing from four to six feet of water, could run upon the river seven or eight months of the year; and adds, from further observation, that it could be navigated nearly, if not entirely, throughout the year with still lighter vessels, say, of thirty inches' draught. What a pity it is that we could not furnish our renowned explorer with a craft like that which El Hami Pasha has had built for his pleasure by Mr. Scott Russell! When will the English nation be capable of doing as much for itself as a mere Turk, with his handful of piastres, compels it to do for him? The heroic doctor was further troubled by the difficulty with which the Pearl backed, when her screw was reversed, in feeling the way along the river's channel. Having entered the river by a side branch-possessing a very good bar and harbour-and explored the delta for about a month, the river was found to be fast falling To prevent the detention of the Pearl, which he was stringently ordered not to delay, the Doctor landed all his goods, on an island, and, at the time of writing, was carrying them up to Tete by successive trips in his small steam-launch. The news sent by him is most encouraging and important. He arrived in the midst of a war between the natives and Portuguese, but, observing a clear neutrality, he has been treated with friendliness by both the belligerent parties, and is endeavouring to push away beyond them with all speed. Of the Zambesi itself he speaks very favourably, entirely confirming the opinion expressed by the two naval officers who accompanied him. On reaching Laputa, where the river is no longer divided into many channels, all difficulties in navigation ended. Here, at Doctor LIVINGSTONE's suggestion, were dug a ton and a-half of coals, the very first ever taken out

THREE NEW MASTER SHIPWRIGHTS have this week been promoted to the Dockyards of Devonport, Sheerness, and Pembroke Dock. The Devonport vacancy has been filled by Mr. JAMES PEAKE, late assistant at Woolwich Dockyard, who has acquired eminence in consequence of his services in devising and Superintending the construction of life-boats; Mr. HENWOOD, late assistant at Chatham Dockyard, and a member of the late School of Naval Architecture, has been appointed to fill the vacancy at Sheerness; and Mr. CRADDOCK, late assistant at Portsmouth, also a member of that School, proceeds to Pembroke Dock,

follows that the merit of the individual is rarely
fully and duly appreciated by his contem-
poraries; and in this, as in many other cases, it
must be reserved for the historian and for pos-
terity to do that justice which can hardly be
expected at the hands of contemporaries.

But in addition to the difficulty of duly
appreciating the merit of the individual who
may have contributed to a successful invention,
there is not unfrequently considerable difficulty
in estimating the merit of the invention. The
merit in general is a question of degree; the
invention has to be compared not only with
what preceded, but with what succeeded it
with the new creations, so to speak, which it
has called into existence. Experience and the
test of time alone can authoritatively decide on
the merit of an invention as an absolute step in
the progress of knowledge, however it may
appear in relation to those by which it is sur-
rounded. Invention is and must be in its very
nature ever progressive; the steps in that pro-
gress may be unduly regarded at the time, but
the course of improvement will ere long clearly
indicate those steps which mainly established
the existing state of advancement.

In connection with this subject, it would not be right to disregard or omit all mention of the operation of the system of patents which has been adopted as a means of encouraging inven

THE CASE OF HENRY CORT, AND HIS tions, and of reward and remuneration for their

introduction, and by which each individual is felt to make the best of the property so recognized in the products of his ingenuity, so that By THOMAS WEBSTER, M.A., F.R.S, &c., &c., the inventor who fails by such means to derive

Barrister-at-Law.
No. I.

that reward and remuneration which he might
reasonably have expected, must be regarded as
presenting an exceptional case.

If the discovery be one not the subject of
those laws, he has a distinct claim as a public
benefactor on the consideration of his fellow-
citizens for some remuneration in respect of his
labour and expenditure of time, money, or other
capital, and for some reward according to the
benefits conferred. If the discovery or inven-
tion be one in respect of which those laws give
such special property, and the inventor has
thought fit to forego, or neglected to avail him-
self of this advantage, he may have claims on
the public similar to those existing in the former
case, if the discovery or invention be one which
may be thus thrown on the waters and aban-
doned to it fate. If the inventor, having
availed himself of the law, and created property
in his invention, has failed to receive the remu-
neration and reward which he might reasonably
have expected, an exceptional case is at once
presented, the special circumstances of which
will require careful consideration before the
claim which may be made can be acceded to.

THE history of inventors and inventions presents
many features well-deserving consideration.
The authors of inventions which have enlarged
the boundaries of science, have extended the
dominion over matter, have added to the com-
forts and conveniences of man, or have increased
the power and wealth of the nation to an
extent which can hardly be estimated, have
lived neglected and died unrequited for the
benefits conferred on mankind. In some cases
the inventors have lived, so to speak, before
their time; in others, the difficulty of introduc-
ing an invention, however meritorious, by
reason of the opposition of existing interests
a difficulty not unfrequently proportionate to
the merits of the invention-or the apathy and
indifference of the public to changes not actually
forced upon them, or the jealousy of competitors,
present sufficient causes for the lamentable fate
of many whom posterity regard as the great
pioneers in the domain of social science and
the progress of useful inventions. This is so
notorious, that the hard lot of some of its
greatest benefactors of their country, as authors
and introducers of useful inventions, has been
made matter of national reproach. Instances,
however, are not wanting in which liberal re-
wards have been granted by Parliament, or by
the Government of the day, to such benefactors,
either by the grant of large sums of money or
by pensions, or by appointment to important
and lucrative situations. The real difficulty
lies in the due appreciation of the individual
merits amidst the host of persons who, in the
case of a successful invention, claim to have had
some share in contributing to that success.
Nor are such claims altogether ill-founded; the
history of abstract as well as of practical science
shows how difficult of attainment and how
small are the steps, so to speak, of discovery or
invention when viewed alone or independent of
their combinations or applications as part of
some system, and as conducive to some special Public attention has been from time to time
results, and when dissociated from, or not asso-called to this, perhaps the most exceptional of
ciated with those elements and conditions which all such exceptional cases; and it may be
are essential to a successful system. Hence it hoped that the survivors of the children of this

For such exceptional cases, special legislation was provided in 1855, by Lord BROUGHAM'S Act, whereby the Crown was empowered to grant an extension of the exclusive privileges in cases of the authors of meritorious inventions, for which no adequate reward and remuneration had been derived. The exercise of this power, on the recommendation of the Judicial Committee of the Privy Council, has provided for the ordinary cases of want of adequate remuneration and reward; but exceptional cases are still of occasional occurrence, requiring special consideration, for which that recent legislation affords no relief.

Amongst such, the case of Henry Cort, the successful introducer of the manufacture of iron, as at present practised, stands most prominent, presenting, as it does, peculiarities which distinguish it from all others.

most meritorious inventor may not be permitted to languish in penury, amidst the universal recognition of the wealth created for the nation by the genius and enterprise of their father.

THE THEORY OF NAVAL ARCHITECTURE.

No. I.

THE theory of naval architecture is readily seen to divide itself into two parts, the first embracing questions which relate to vessels floating quiesthose which relate to vessels moving through the cently upon the water, the second comprising water under the action of some propelling power. The whole of the questions in the first division may be solved in all their ramifications, like other statical problems, as certainly as any proposition in plane geometry. In the second division there are many which might be similarly solved, at least in parts, since a body in uniform motion may be looked upon as being in statical equilibrium, and there are consequently relations known to exist among the forces exerted upon it, although the forces themselves-depending as they do for their amount and the directions of their action upon the laws of the resistance of fluids-are unknown to us.

The first division is very extensive, and every constructor who wishes to know what kind of ship he is designing, and what qualities it will possess, should be able to investigate for himself the considerations embraced by it. Of the second division, the principal questions relate to the position in the ship of the masts and spars, or rather of the centre of effort of the wind on the sails as regards both length and height, in order that the ship may work well with a given amount of canvas, and not heel over to too great an angle under it.

man

In considering the construction of a new ship, the first conditions which have to be fulfilled are that the ship when built, rigged, stored, and if she be a merchant ship, or the required armamanned, may be able to carry the required cargo, ment, ammunition, &c., if she be a of war-if a steamer, the engines, boilers, and sufficient coal besides. The ship must carry these without either sinking too deeply in the water, or floating too lightly upon it. These conditions must also be fulfilled with minimum dimensions, for in proportion to the size is the cost of the vessel; to build a larger ship than necessary is to incur unnecessary expense; to build one too small to carry her weights is to render the whole expense useless.

tian era, showed that the depth to which any Archimedes, nearly 300 years before the Chrisfloating body sinks in the fluid, is such that the weight of the fluid displaced is equal to that of body. We do not, however, find that the observed fact was then taken advantage of for practical purposes. In early times in England, probably until Sir Anthony Deane became the constructor of ships for the Royal Navy, new ships were mere copies of others already in existence, with trifling alterations to answer particular purposes, or to correct existing defects. Constructors could not then move far out of the beaten track, but had to wait patiently for results until the structures which they reared floated in their native element. Pepys, in his Diary, 1666, says :-"Mr. Deane and I did discourse about his ship, the Rupert, which succeeds so well, as he has got great honour by it, and I some by recommending him. The King, Duke, and everybody say it is the best ship that was ever built. And then he fell to explain to me his

manner of casting the draught of water which a

ship will draw beforehand, which is a secret the that hath come to any certainty beforehand of King and all admire in him, and he is the first foretelling the draught of water of a ship before she is launched." The secret referred to was this: That the weight of a volume of water equal in bulk to the part of the ship below the water's surface, is always equal to the weight of the ship and its contents; and possibly, though not probably, the corollary from it,-that the

centre of gravity of the volume of water displaced is always in the same vertical as the centre of gravity of the ship and its contents. These propositions we shall now prove. Let C

B

floating body with its contents and that of the
water displaced, we also learn that for every
weight put on board of a ship there is an equal
weight of water displaced by it. Of the know-
ledge of this fact we shall avail ourselves when we
have to discuss the question of stowage, and we
shall find that, by its judicious application, our
calculations will be found very much abridged
when compared with those generally in use.
That the centre of gravity of the ship with its
contents is always situated in the same vertical
line as the centre of gravity of the displacement,
asmuch as the centre of gravity of any floating body
does not admit of a simple practical illustration, in-
and its contents is not generally directly obtainable.
But an ingenious person will have no difficulty in
proving it by experiment to his own satisfaction.
As we said before, however, this follows as a ne-

wards.

as represented in the figure, and the weight W hanging vertically under it, supported by the tension of the rope. It would be entirely immersed, were it not for the effect which the immersion of the weight and the rope has on the vessel, that effect being to raise it a little out of the water-the part emersed being equal to the volume of the weight and of the rope, diminished by a quantity of fluid the weight of which is the same as that of the rope.

On this principle, sunken vessels are often recovered in the following manner :-At low water, one or two ships or barges, are attached by strong a number of empty casks, air-tight caissons, cr ropes or hawsers to parts of the sunken ship, and the ropes are hove in tight. As the tide rises, the vessels become more and more immersed in the water until the weight of the additional volume of water displaced by the whole of them equals the nearly at its height, the vessels, with the sunken force necessary to raise the ship. When tide is ship under them, are removed towards the shore In consequence of the necessity for this until she touches the ground again. If the ship equality of the weight of the ship and of the be then in such a position that the falling tide water displaced, we perceive that, if the water in will leave her above water when at its lowest, the which a ship floats at different times differs in vessels are cast off: but if not, they are hove down density, there will be a corresponding difference as before, and the process described is repeated. of a cubic foot of sea water is a little more than a sunken ship may be thus approximated to. On The number of air-tight vessels necessary to raise in the immersion of the ship. Now, the weight 64 lbs., and the weight of a cubic foot of river the sunken ship the pressure downwards is the water about one-fiftieth less. A line-of-battle weight of the ship and of the cargo, and the ship like the Agamemnon, when ready for sea, pressure upwards is the weight of a volume of weighs about 5,000 tons, and it requires 26 tons water equal to that occupied by the materials of to increase her immersion one inch; consequently, the ship and by the cargo. If the ship be built were such a ship to come direct from sea into the of wood, the specific gravity of the mass could not river, keeping precisely the same weights on board, much exceed unity-that is, the weight of the she would sink 3x6 inches, or 4 inches whole mass would be about the same as that of an (very nearly) deeper in the river than when at sea. equal volume of water. Ships which have flat floors, and are full forward remain to be overcome by the water-tight vessels a pressure equal to the weight of the cargo when and aft-approximating, in fact, to the form of a rectangular box-as are some colliers, barges, &c., placed in water. This pressure can often be found will sink just one-fiftieth deeper when in river very readily. water, than when at sea.

be any floating body, a ship, for instance, and
AB the surface of the water. Imagine the body to
be lifted up vertically out of the water, and the
water surrounding the ship to retain the imprint
after the body has been removed; and further
imagine this space to be again filled with water to
the same level as before. The volume of water incessary consequence from the equality which has
this space is evidently the "volume of water dis- water upwards, and the weight of the body down-
been proved to exist between the pressure of the
placed by the body," and it is called, as is also its
weight, the DISPLACEMENT. Its centre of gravity
is denominated the CENTRE OF GRAVITY OF
DISPLACEMENT; or, more briefly, THE CENTRE OF
BUOYANCY. The particles of water which we
imagine to retain the imprint of the body, now
support the volume of water which the body dis.
placed, in the same manner as they supported the
body itself when it was immersed. Each of these-
the water displaced and the body immersed-must
then be supported by the same pressure acting
upwards. And since the weight of the body
would be sustained by the same upward pressure
as now supports the weight of the water displaced
by the body, the weight of the floating body must
be equal to that of the water displaced that is, to
the Displacement. Again: When the body
is immersed, the pressure downwards is the
weight of the body-the pressure upwards, a
pressure equal to the weight of the water
displaced. These two may be considered as
forces acting the one at the centre of gravity
of the body, and the other at the centre of gravity
of the displaced water, each in its respective direc-
tion, and the two being equal to each other, there
can evidently be no equilibrium unless their lines
of action coincide-that is, unless the centres of
gravity of the body and of the displacement lie in

the same vertical line.

That the weight of the water displaced by a floating body is equal to that of the body and all its contents, may be practically proved by apparatus within the reach of every one. Take two vessels, A and B, as represented in the figure; place

B

one within the other, and fill the upper one with water to the brim: then take another empty vessel, C, and lower it gradually into the water in B, until it is supported by the pressure of the water. When C is at rest, a volume of water equal to that displaced by it has run over into A; and if this water be placed in one side of a pair of scales, and the vessel C in the other, they will be found to balance each other. Replace C in the water, and gently dropsome heavy material, such as sand or shot into it, and more water will overflow; remove C with the material it contains carefully to one end of the balance, and add to the water before put in that which was caused to overflow by the introduction of the material into C, and, as before, the water will balance the vessel and its contents. This may be often repeated, until C sinks nearly to its upper part, and it will be found in every experiment that the weight of the water which has overflowed from B is always equal to that of C, and of the material it contains.

From these practical proofs of the equality which always exists between the weight of the

000

26

The necessary equality already discussed also explains why heavy metals swim in a vessel containing mercury in its ordinary fluid state. The specific gravity of mercury is about 134, whilst that of iron is about 7; it will therefore be readily seen that a mass of iron, 13 inches deep, with vertical sides, will only sink 7 inches in the mercury, and will float in the same manner as a piece of wood floats on the water.

We have already proved that a floating body presses downward, and is pressed upwards, by forces equal to its weight. If, now, a light airtight vessel, such as an empty cask, be placed in the water, it will float, until it be loaded with a weight equal to the difference between its weight and that of an equal volume of water. Let one end of a rope be secured to the weight, and the other end to the air-tight vessel; throw the

weight into the water, and as soon as the equili-
brium has been restored, it will be found that the
vessel is nearly at the surface (A B) of the water

There would then

When known, we must have a number of water-tight vessels, such that their weight, together with the weight of cargo when in water, shall equal the weight of the volume of water displaced by these vessels. If the ship be built of iron, with the usual amount of wood work, the weight of the whole would be about five times the weight of a volume of water equal to the bulk of the materials. In addition, therefore, to the difference of the weight of the cargo and that of a volume of water equal to it-that is, to the weight of the cargo in water-four-fifths of the entire weight of the ship has to be overcome by the pressure of the immersed water-tight vessels. We perceive, therefore, that although an iron ship may be lighter than a wooden one of the same tonnage, yet, were the two sunk with the same cargo on board, the labour necessary for raising the iron ship would be much more than that required for raising the wooden ship, as might have been expected.

It will be thought by some persons, perhaps, that these considerations do not belong to our subject. But it is only by such illustrations that fixed principles are gained, and the student in naval architecture is made familiar with the various phases under which the same problem appears, and it is our intention at all times thus to illustrate whatever we discuss whenever it can be made more clear by doing so.

To return to the displacement: we have seen that the displacement is always equal to the weight of the ship. The consequence of this is that the two are spoken of indifferently; and it is only when speaking of the centre of gravity of displacement, and the centre of gravity of the ship, that we are made aware by the terms that they are not synonymous.

The weight of any vessel cannot be very accurately assigned by calculating the weight of the several parts composing it, even when the timbers and planks are straight-as in some barges-because of the great differences which exist in the specific gravities of timbers of the same species. And in calculating the weight of a ship of the usual for m in this way, besides the errors which creep in on account of the variations in the specific gravity of

the timber, others arise from the difficulty of ob- The committee are happy to say that this
taining the correct contents of curved timbers. attempt at practically inquiring into the pecu-
These causes of error taken together render the liarities of construction to which the good or bad
result obtained by this method very questionable, qualities of steam-ships may be attributable, has
even when the greatest possible care and labour not been wholly fruitless, for, although ship-
have been expended in the operation. But, after owners, ship-builders, and marine-engine manu-
the ship is completed and floating in the water, facturers have been generally reluctant to com-
since we know that her weight is equal to that of municate particulars whereby the dynamic merits
the water she displaces, we have only to find the of ships may be numerically classed and compared,
cubic contents of the part immersed, multiply it the results of which classification and comparison
by the weight of a unit of volume of water, and might, if promulgated, affect the commercial
the result is the weight of the ship and every-value of their property, and the relative pro-
thing in it.
fessional reputation of constructors, still, in reply
to the before-mentioned circular, information has
been communicated, as to the performance of
vessels, particularly steam vessels, by which it
appears that a great difference exists between
steam-ships as respects their economic capabilities
for the performance of mercantile steam transport
service, leading to the conclusion that the general
aggregate of steam service is performed by vessels
of inferior adaptation for economic duty, and con-
sequently at a rate of prime cost expenditure, and,
therefore, ultimate charge on the public, greatly
in excess of that which would be involved if all
steamers were of the superior class of excellence
that has been already, in certain cases, actually
attained. For example: this committee are assured,
on authority which they believe to be unques-
tionable, that a certain vessel, the Bremen, of 3,440
tons displacement at the time of trial, propelled
by engines working up to 1,624 indicated horse-
power, attained the speed of 13.15 nautical miles
per hours. Now if we esim ate the dynamic duty
thus performed by the
formula V3 D

When the ship is of any regular form, the volume of displacement may be found by the ordinary rules of mensuration. Ships are, however, usually of no regular figure, their sections conforming to no other law than the will of the constructor; consequently, whatever methods may be employed to find the displacement, they cannot be more than approximations. These approximations, however, as we shall hereafter show, may be made to approach the actual amount as nearly as we please.

SHIPPING STATISTICS.

IT will be recollected that a committee was appointed by the British Association in 1857, to inquire into the statistics of shipping, with a view to rendering statistical records more available as data, and more conducive than heretofore to the improvement of naval architecture as respects the adaptation of the form of ships to the require ments of sea service. The committee so appointed consisted of the following gentlemen :

Admiral Moorsom.
J. Scott Russell.
J. E. McConnell.
Charles Atherton.

William Fairbairn.
James Perry.
Henry Wright.

Andrew Henderson. The committee, on commencing their proceed ings, received letters from Admiral Moorsom, Mr. J. Scott Russell, and Mr. J. E McConnell declining their co-operation as members of the committee. The remaining members, however, agreed to prosecute the duties assigned to them, and W. FairLairn, Esq., F.R.S., by the unanimous desire of the committee, undertook to conduct the proceedings as chairman, with the assistance of Henry Wright, Esq., as honorary secretary.

The following is the report which the committee made to the British Association at Leeds in 1858, the publication of which has not heretofore been authorised. We are indebted to the

Editor of the Journal of the Society of Arts for an early copy, forwarded at our request.

The Report runs as follows:-

In the first place, the committee issued a circular, inviting statistical information as to the actual sea performances of ships, with a view to compiling a comprehensive statement as to the sca performances of vessels generally, whence the committee might be enabled to select a considerable number of vessels, of which the performances at sea may have been remarkable; and their attention being thus directed to a limited selection embracing a considerable number of vessels of practically established excellence for sea service, the committee hoped, after making due inquiry, to be enabled to present, as respects these vessels, a statistical exposition, in tabular form, of their various elements of construction and type of build; and thus, by a system of collation and induction, to discover practically those types and elements of construction which have been found by experience most conducive to good performances at sea. In the case of steam-ships, it was purposed that the statistics of the original trials to which steamers are generally put when new, should also be collected, classified, and collated with reference to the subsequent performances of the same vessels at sea, whence it might be determined to what extent and in what respects the usual smooth-water trials of steam-ships may be indicative of the probable properties to be expected of the same ships at sea, as respects their dynamic capabilities.

=

C, we shall have the co efficient,

Ind. h.p.
C = (13·15) X (3110)

1624

=

2274 x 227.88
1624

=

319,

and this co-efficient of dynamic duty, resulting
from the mutual relation of displacement, speed,
and power, appears, from the statements which
have been communicated to this Committee,
nearly 50 per cent. higher than that realized by
the average performance of the steam-ships of the
present day. The following are the co-efficients
of dynamic duty deduced by the foregoing rule
from the performance of mercantile steamers of
high repute, of which the trial data have been
communicated to this Committee, viz., 325, 291,
291, 288 259, 218, 231, 230, and 201, and many
others below 200.

This Committee, therefore, regard the Bremen
as being a felicitous exemplification of naval
architecture as respects type of form adapted for
easy propulsion; and as we conceive that the
promulgation of some of the constructive elements
of this vessel may be of public importance, we are
happy in being authorised and enabled, by Messrs.
Caird and Co., of Greenock, the constructors of
the ship and of the engines, to communicate to
the British Association the following statistical
data as to the elements of construction of the
Bremen:-

The foregoing data afford all the particulars required for the construction of Peake's curve of vertical sections, whence may be deduced the position of the vertical line passing through the centre of gravity of displacement, and also the positions of the centre of gravity of the fore and aft bodies respectively.

It will be observed, from the foregoing data of the constructive elements of the Bremen, that the maximum immersed section is at the middle of the length, and that the vertical sections are in such ratio to each other, with reference to their res pective positions, that the curve of vertical sec. tions will be a close approximation to a parabola.

The ratios deducible from the foregoing particulars of constructive data, combining Peake's curve of immersed vertical sections with the curve of displacement, will give a close approximation to the type of form of the immersed hull.

The engines of the Bremen consist of two directacting inverted cylinders, 90 inches diameter and 3 feet 6 inches stroke, fitted with expansion valves capable of working expansively to a high degree. All parts of the engines are felted and lagged with wood wherever practicable, the lower 16 feet of the funnel being surrounded by a casing forming a superheating chamber, the steam entering at the lower end, and passing off at the top into the steam pipes leading to the cylinders.

(To be continued.)

THE SMITHFIELD CLUB SHOW. (Continued from page 7.) IN resuming our notice of the late implement show, we should not omit to mention the growing interest which is being manifested in the system of "guideway" steam cultivation, introduced and practised by Mr. P. A. Halkett, of 80 Chancerylane, who is now engaged in forming a company to carry it out upon a comprehensive scale. Its general principle has been often described, and is probably known to most of our readers; but the attention of the agricultural public having been lately drawn to the subject from Mr. Halkett's paper, read before the Society of Arts, and which gave rise to an interesting discussion, we may be excused for saying a few words at this time. At a recent meeting, at the Freemasons' Tavern, when the guideway system of cultivation was discussed, several gentlemen spoke in very high terms of it; Mr. Mechi, Mr. Robert Scott Burn, and Mr. Wren Hoskyns, being amongst the number. The system (by which the whole operations of agriculture are proposed to be, and have actually been, performed by steam-power) consists in laying down, at intervals of fifty feet or more, permanent rails, upon which travels à locomotive cultivator, carrying its own motive power, and to the under-side of which are attached the various implements to be used in cultivating the land. On the headlands rails are laid at right angles to the former, upon which a shunting or traversing carriage moves, by which means the cultivator is transferred from one set of rails to another, or is brought to the homestead, where the engines can be used for thrashing or other barn operations. Upon this plan it will be seen that no weight bears upon the land, thus admitting of its being cultivated in any weather or state of the ground, leaving, it is said, the heaviest clay soil in a state of lightness impossible to arrive at where the weight of men, implements horses, or steam-power is constantly "poaching" it; whilst by consecutive ploughings in the same furrow, length, mca- 256 5 sq. ft. it can be cultivated to any depth required. The crops are carried off, and the manure carried on to the land by the same means as other operations are performed; and when we consider the great weights to be moved and the distances over which 300 tons. they must be borne, we may conceive some of the advantages of a smooth road, both as regards saving of time as well as of cost. The quantity, says Mr. Halkett, that can be ploughed per day with power suitable to a farin of 1,000 acres, is 25 acres, and three men are all that are required to conduct the

Length between perpendiculars of stem and

rudder post Breadth of Beam.. Depth of hold

Mean draught of water at the time of trial
Displacement (D) at trial draught
Area of maximum immersed section (A) at the
trial draught..
Distance of maximum section (A) measuring
from the stem

318 feet.

40

26 ""

18ft. Gin. 3440 tons. 606 sq. ft.

159 feet. forw...18 feet.

aft.

Constructors' load draught.
Displacement at constructors' load draught
Rate of ships' displacement at constructors'

19
3410 tons.
25 tons
per inch.

load draught..

operation. This calculation, he states, is based arrangements which allow of a much greater
upon work which has been actually and repeatedly variation being made in the size of the broken
performed. As, however, when time presses, a pieces of cake than those hitherto made. Mr.
double set of men may be employed, double this Nicholson's oil-cake breaker, of which the one
amount of ploughing may be done in the twenty-now noticed is an improvement, obtained a prize
four hours, the operation being capable of being car- at the late Chester meeting.
ried on both by day and night. It must be apparent Clayton & Shuttleworth exhibited one of their
to all, that by no possible system could greater pre-well-known single blast combined machines, which
cision in the work be attained than by one in performs the various operations of bolting, thrash-
which, as in Mr. Halkett's system, every opera-ing, straw-shaking, riddling, winnowing, chaff
tion may be gauged almost to within half-an-inch. separating, and barley horning. To this machine,
Indeed, hoeing has been done without injury to
in many cases, is added a blower and separator,
within that distance of the plants. The cost of for finishing the grain for market, the tail being
the guideways, if of creosoted timber, is calculated separated from the good corn, and the whole de
at £10 per acre, or if of hard burned brick and livered into four sacks-marketable corn, best tail,
angle iron, £20 per acre; while the cost per acre
of various operations for a farm of 600 or 1,000 entering the screen.
chicken corn, and light particles blown out before
These machines are fitted
acres, is set down as follows:-ploughing 5in, by with patent drums and improved straw shakers.
10in. furrows, 1s. 7d.; hoeing, 3d.; scarifying, The fixed barn works of this firm are well known,
grubbing, &c., 8d.; harrowing, clod crushing, and combine thrashing and dressing machines,
rolling, 5d.; drilling or dibbling seed, 5d; reap-
corn and tail elevators, necessary shafting, and a
ing (cutting and delivering) at 60 acres per day, self-acting sacking apparatus, for weighing the
84.; underground watering crops, at the rate of sacks, and calling by a bell, at the proper time, the
3,000 gallons per acre, 1s.; surface watering,
1. 2d.; carriage of manures, &c., d. per ton per replace it by an empty one.
man in attendance to remove the full sack, and
mile; and, finally, deep cultivation, to the depth Shuttleworth also exhibited one of their small
Messrs. Clayton &
of 25in., 12s. per acre. The mode of cultivating horizontal fixed steam engines, about which we
to this depth has been performed by first using need not further remark than by saying that their
six ploughs, cutting six furrows simultaneously of workmanship is of the very best kind, and such
five inches depth; then ploughing again to a fur-
ther depth of five inches; and at fifteen inches only as can be ensured by the most perfect
arrangements for their manufacture. Although this
below, through the subsoil of a hard yellow clay, firm proceed very cautiously in the introduction
an anchor was drawn, with a palm nine inches in
width; thus ploughing and breaking up the nothing is neglected which they consider to be a
of changes in their machinery, yet the adoption of
ground to a depth of twenty-five inches. This real improvement to any of the machines which
depth of cultivation is sometimes attained by
they construct. We believe of portable engines
market gardeners by trenching, and, it is said, costs alone, they have turned out between 2,000 and
£10 to £12 per acre. Whether or no it be pro- 3,000 during the last few years-a great number
bable that more extended practice will verify the
statements here made as to the cost of various having been sent abroad, the greater part of the
agricultural operations, it is perhaps impossible to foreign trade in portable engines being done by
say; nevertheless, enough has doubtless been done
to fully justify extended trials, especially when
we remember how much success in agriculture, as
in manufactures, depends upon methodical modes of

them.

William Cullingford, of Islington, exhibited his
simple but very cleverly-arranged bird nets,
which, when set, are entirely hidden from the
bird, but which spring up and make a captive
the moment the delicately balanced board upon
which the bird alights is touched.
may be had complete for 10s. each, being chiefly
intended for trapping larks.

The nets

working, which, when introduced in the latter case,
have never failed not only to cheapen production,
but also very greatly to improve the things pro-
duced. We trust Mr. Halkett may succeed in
inducing those whose interest it is to set them-
selves soberly to work to test, on a sufficient scale, Hughes and Sons, of the Great Dover Road,
the importance of his system. Daring the show, exhibited a new "ring" stone (Pym and Rand's
and for some days subsequently, Mr. Halkett ex- patent), the object of which is to grind faster and
hibited his cultivating apparatus in the neigh-cooler than ordinary stones. The top stone on this
bourhood of London.
plan stands, while the bottom one runs. Messrs.
Powis, James, & Co., of 26 Watling-street, ex-
Euston and Amos are fitting several of these
hibited their endless band-sawing machine, capa-novations deem Hughes' ordinary 4 feet stones, with
stones to new mills; but those who are against in-
ble of being worked by hand or steam power, as
also their circular-saw bench, also adapted for
hand or steam power. These machines, although
not new, have not, we believe, been before exhi-
bited by the firm at any of the Smithfield shows.
They also exhibited an admirable combined ma-
chine for morticing, tennoning, and plaining,
capable of being worked with ease by hand-power,
and performing the operations with the greatest
nicety and very great ease.

Joseph Lardner, of Banbury, exhibited his chaff cutting machines, the peculiarity of which consists in the knives being divided, thus rendering the labour of working more uniform, and, conse quently, less exhaustive than when they are of the usual length. Another feature in these machines is, that the legs are made of wrought iron, the tops being cast as usual.

the dressing known as "fourteen threes," as the
best. The new stones are beautifully put together,
and if the principle upon which they are con
structed be sound, which we think it is, there is no
fear of failure ass the workinanship is perfect.

A. B. Child, of 192, Tottenham Court Road,
exhibited his new grain separator combining the
action of the blast, screens, and suction, and suit-
able for dressing both English and foreign grain.
These machines are made for cleaning from 300 to
400 bushels per hour.

Barrett, Exall, and Andrewes exhibited one of their two horse portable engines, which, at the Chester trials, was found to be exceedingly economical in fuel; as also one of their well-known fixed horizontal engines, which gained the first prize at Chester. These engines, when equal to, Dray and Co., of Swan Lane, exhibited, in ad- or above, 10-horse power, are fitted with conden dition to their usual collection of implements, a sers, which greatly reduces the consumption of new hand-dibble, invented and made by Mr. H. fuel. One of this firm's fixed horizontal condensing Bek, of Lamberhurst, Kent. This dibble we care-engines gained the 600f. prize and a gold medal fully examined, and do not hesitate to say, that it possesses strength and simplicity in an eminent degree It is adapted for sowing various-sized sads, including mangold wortzel seed, as well as

beins, and is capable of being easily adjusted to suit the particular work required to be performed. Samuel Nicholson, of Newark, exhibited a new double-barrelled oil-cake breaking machine, with

at the Paris Exhibition, and was much commended
by M. Caille, the well-known extensive manufac-
turing engineer of Paris.

As we have still upwards of thirty stands to
notice, we must postpone further comment until

next week.

PREMIUMS FOR INVENTIONS.

THE Council of the Society of Arts, in issuing a
list of desiderata as subjects for premiums during
the sessions of 1858-59, and 1859-60, urge upon
their members and the public the importance of
communicating detailed accounts of new processes
in arts or methods of manufacture of any modifi-
cations by which these may be simplified, or labour
saved, and of any novel application of raw
materials, whether previously known or not, to
useful purposes. It is quite possible that some
of the things set down in their list as to be done
may have been already accomplished; but, in
of the objects of the society is to elicit discussion
such cases, the knowledge of them is limited. One
on the subjects with which it deals, to see that
nothing is concealed which may in any way tend
and opinions. The weekly meetings, and the
to promote the good of all, and to record facts
Journal of the Society of Arts, afford the requisite
facilities for effecting this, and the council
earnestly hope that the
opportunities thus given
may be taken advantage of. Patented inventions
are not excluded from receiving the society's
rewards. The society is willing to receive com-
munications on subjects not included in the follow-
ing list, but in all cases expressly reserves the
power of rewarding any communication according
to its merit, or of withholding the premium alto-
gether. The degree of originality and extent of
suggestions for improvements will have material
influence on the adjudication of the award. All
communications must be written on foolscap
paper, on one side only, with an inch and a
quarter margin. They must be accompanied by
such drawings, models, or specimens, as may be
necessary to illustrate the subject. The drawings
should be on a sufficiently large scale to be seen
from a distance when suspended on the walls of a
meeting-room. In regard to colonial produce of
all kinds, it is absolutely necessary that a certifi,
cate from the governor, or other qualified person-
should accompany the samples sent to the society
certifying that they really are the produce of the
particular district referred to.
The samples
should be sufficient in quantity to enable experi-
ments to be made, and an opinion to be formed of
their quality; and it is desirable that the cost
price in the district from which they are for-
warded should be given. In every instance the
probable extent of supply, with the average yield,
if cultivated, and whether similar articles have
hitherto been exported from the colony, or not,
and in what quantities, should be stated. All
communications and articles intended for compe-
tary, at the society's house, free of expense, either
tition must be, delivered, addressed to the secre-

on or before the 31st of March, 1859, or on or
before the 31st of March, 1860. In the first case,
they will be considered during the session 1858-59,
in the second case during the session 1859-60.
This restriction, as to the date of receipt, does not
apply to articles of colonial produce, in respect of
which this list is valid until the 31st December,
1860. A list of subjects for premiums may be had
on application (by letter) to the secretary of the
society.

THE CORT FOUNDRY AT GOSPORT.-There is a curious circumstance worthy of mention regarding the foundry at Gosport, in which the celebrated Cort worked out all his important improvements in the casting of iron. The foundry had been shut up for a long time, until a few years ago, Mr. Cunningham, the inventor of the now wellknown Cunningham System of Reefing from the Deck," took the premises for the purpose of working out his great invention. The foreman of the smiths employed by him, happened to be a very clever workman of the name of Carote or Cort, and supposed to be a descendant of the same family as the great iron founder. Thus two great inventions, each of which has conferred upon the

world incalculable benefits, have beca wrought out in the same place, and the name of Cort has been in connection with both of them.