and extensive adoption. What its cost may
prove to be we do not know; but, other things
being as we have stated, the cost of it is a
matter of minor importance.

THE NEW IRON STEAMSHIPS FOR THE
NAVY.

iron-sided vessels.

ability of Messrs. Easton and Amos, the cele-
brated engineers, at whose works they have a
very large machine nearly completed. Their
method of forming the cable may be briefly
stated as follows:-They commence by covering
the conducting wires with a spiral layer of grey
or unbleached cotton, as being the most pure.
They then cover the cotton with strips of rubber
cut from the bottle or other form in which it is AT a discussion which took place at the Society
imported, without being masticated or otherwise of Arts, on Wednesday evening (May 3), after the
operated upon, laying on the strips spirally, and reading of a lecture by Mr. Leonard Wray, on
with overlap. This employment of "pure" rubber timber for ship-building, Mr. E. J. Reed, one of the
for the first coating of the wire is a very impor- Editors of the MECHANICS' MAGAZINE, (whose
tant point, and evinces the practical knowledge paper on the ships of the Navy recently excited
of the inventors. They then wind round outside much attention) made the following remarks:-
of the spiral layers of rubber a thread of vul- "However unfit the iron ships which have hitherto
canised rubber covered with cotton. The effect been constructed for war purposes may have pro-
of this elastic thread is most remarkable. Being ved, we are undoubtedly about to return to the
use of iron in the construction of such vessels. It
always in tension, owing to its elasticity, it so
will be in the recollection of the gentlemen pre-
effectually compresses the layers of pure rubber
sent that nine or ten weeks ago Sir John Paking-
beneath it as to firmly consolidate them into one
ton announced in the House of Commons that,
substance, incapable of being again separated whatever may be their cost, we had no option but
without great difficulty, and sometimes not at all.
to commence the construction of iron-coated ves-
They perform all the coverings at one operation, sels. The reason alleged by him for this was two-
and employ for the purpose a spiral covering ma- fold; in the first place, he said, the experiments
chine to lay on the several coverings in the made with Sir William Armstrong's gun had
order above described. In some cases, in place shown that thick iron might be employed with
of the covered thread of vulcanised rubber be- advantage as a defence for the sides of ships; and
fore mentioned, or in addition thereto, they in the second place, that the French had two ships
apply further spirally-laid coverings of pure thus defended fast approaching completion. Since
rubber laid on alternately in opposite directions, that speech of Sir John Pakington's was made,
and envelope the whole in a similar covering of
we have received a report made to the Treasury
vulcanised rubber or not as may be desired. in January last, from which I draw the autho
The whole of these operations may be performed rity to state that the French were then actually
in one machine. Having thus effectually in- These vessels, it is stated, are to be substi-
preparing four of these
sulated the wires, they further protect them by tuted for line-of-battle ships. Their tim
applying a coating of gutta percha of the ordi-bers (for they are built of wood) are of the
nary kind, where that may be found desirable,
and surround this gutta percha with plain hemp
(free from oil, tax and grease) braided on.
Where gutta percha is not used, the plain fibre
is laid immediately upon the insulating ma-
terial. Then they braid or wrap on a coating of
spun yarn saturated with tar or other pre-
serving substance. The spun or tarred yarn or
wrapping of rubber is then protected by wires
laid on by means of a cleverly-arranged hollow-
tube braiding machine at one operation, whereby
one set of wires is laid longitudinally without
any twist, while another set forms the braiding,
and encloses the longitudinal wires. The ad-
vantage in using a braiding machine of their
construction for covering telegraphic cables is
beyond dispute, as by means of it cables can he
made of any strength required, and of almost any
required lightness, and at the same time be free
from twist, and have all the strain taken off the
conducting wires during the paying out of the
same into a deep sea. It appears, also, that
scarcely any strain whatever is brought upon
the core during the application of the external
iron covering, which is by no means the case in
cables covered with spiral wires. In them the
core is subjected to a very great strain, and the
insulation is thereby seriously damaged. The
inventors, of course, lay no claim to the use of
india-rubber for the insulation of telegraph
wires, but limit their claims to the improved
methods and means of applying it.

Specimens of cables manufactured by Messrs. Hall and Wells have been submitted to us, and we say, with no kind of hesitation, that the insulation of the wires of the same is as good as it is possible for it to be-and that is much more than we can say of many specimens that come before us. Nor is the insulation only good; the cable is also light, very strong, very elastic, and very little liable to derangement of any kind during the handling of it, either in shipping it or in paying it out. We shall not urge its merits upon telegraphic engineers and companies, as they must win for it a speedy

scantling of a three-decker. They are to carry
36 heavy guns, most of them rifled 50-pounders,
which will throw an 80-lb percussion shell. We
are told in the report that the naval men of
France seem to be so convinced of the irresistible
qualities of these ships that they are of opinion
that no more ships of the line will be laid down,
and that in ten years that class of vessels will
have become obsolete. We have still further in-
formation to the effect, that no less than eight of
the ships are in contemplation by the French
Emperor, the construction of six of them being
fully determined upon. These vessels will not
prove very efficient ships in many respects.
cannot be very fast; nor can they be
With engines of 900 horse power only, they
pected to

ex

the

defended portions of the vessel that, should the latter become riddled by shot, and water-logged, the vessel would still be sufficiently buoyant to float, and maintain the action in which she happened to be engaged. I am very sorry to say the Admiralty have lost time in proceeding with this great and most necessary undertaking. Sir John Pakington promised the House of Commons that he would not lose a moment in bringing these ships into existence. But two months and more have passed since then, and yet no contract for building a single iron coated ship has yet been issued. I fear we must impute to the extravagantly imaginative speech of Lord Clarence Paget a part of this delay, for the Admiralty departments have had much to do in the way of vindicating themselves from his unmerited attack. It takes much time to go over the ten years' accounts of such a department as the Admiralty. Still for my part, I think delay on such grounds is scarcely justifiable. It would be better for such a speech as Lord Paget's to go unanswered altogether, than to withdraw our strength for months from an undertaking by which alone we can maintain an equality with France. In the hope that my words may find their way into the public papers, and thus reach the eyes of our Government, I bring this subject to your attention. It appears to me scarcely fair to this great iron-ship-building country to allow it to fall behind France in this matter."

Proceedings of Societies.

UNITED SERVICE INSTITUTION.

the theatre of the above institution "On the AdvanApril 29.-General Portlock delivered a lecture in tage of cultivating the Natural and Experimental Sciences, as promoting the social comfort and practiaudience, among whom were Sir William Gomm, cal utility of Military Men," before a numerous K.C.B., Generals Cameron and Drummond, and other distinguished visitors. In the course of the lecture General Portlock spoke of the ill consequences of adhering to the narrow view adopted by many, of considering every branch of knowledge useless which cannot be shown to have a direct practical bearing either in the production of wealth or in the special business of a profession. It is impossible, he observed, to lay down as a rule that any knowledge once acquired may not prove the means in after life of overcoming difficulties otherwise insurmountable, but further than that, education must always be considered as not only intended to supply the knowledge actually required in the prosecution of some definite profession, but also to supply the mind with a wholesome nutriment which should keep it from preying on the body.

INSTITUTION OF ENGINEERS IN SCOTLAND.

the Queen's Hotel, George square; Dr. W. J. April 28.-The anniversary dinner took place in Macquorn Rankine, President, in the chair, and Walter Neilson, Esq., President elect, acting as croupier.

But prove very handy. important fact to be observed with reference to them is, that they may fairly be expected to prove proof to both Paixhans and Armstrong shells, and you may judge for yourselves what would be the effect of half-a-dozen shell-proof frigates making their appearance among a fleet of our wooden ships. In order to avert such a disaster as this Sir John Pakington obtained a grant of money from the House of Commons to enable him to build a few shot-proof ships for our own Navy, and called upon private ship-building firms, and also upon his own inaster shipwrights, to furnish deAs soon as these designs signs for such vessels. were received, if not before, it became perfectly evident that the most efficient method of constructing the shot-proof frigates would be to build them wholly of iron. This has been fully decided upon. I believe the main reason of this is to be found in the fact that it is not practicable to cover the whole of the exposed portion of the ship with thick iron, on account of the weight, and it would not, of course, do, in these days of explosive shells and liquid exposed. Consequently, the resort to iron alone fires, to leave any portion of a wooden ship became absolutely necessary. That the uncoated portion of the ship will be open to what the lec-greatest benefit upon the military art by their im turer of the evening has denominated the 'dis-provement of implements of war, such as those inastrous liabilities of a thin iron structure' is most troduced by Whitworth and Sir W. Armstrong, which had brought the art to a degree of perfection never certain; but the difficulty is got over by so pro- attained before. For this reason civil and mechanical portioning the volumes of the defended and un-engineers should look upon those who professed the

The CHAIRMAN, in proposing the Army and Navy, referred to the fact that in former times there existed no distinction between military and civil engineering, both branches being practised by the same individuals. It was worth remarking that the great military commanders of antiquity were engineers-a circumstance to which, in a great measure, their success and skill as soldiers was owing. Julius Caesar was a consumimate engineer, as would be seen from his "Commentaries," a great portion of which he devoted to the description of the engineering works erected by himself. Leonardo da Vinci was a skilful engineer, as also was Michael Angelo, and Benvenuto Cellini was a military engineer of the highest merit. In modern times, however, owing to the division of labour, and to the cultivation of the arts of peace, civil and military engineering were generally regarded as distinct professions, but there was, nevertheless, a strong connection between them; and he was glad to see that recently the intimacy between both was beginning to be recognised again. Civil and mechanical engineers of the highest eminence had lately conferred the

military art with interest and sympathy. Then as regards the navy, he need scarcely remind them of their intimate connection with that branch of the service, since they must all be aware that the success of our fleets must depend on the construction of swift and strong ships, and the machinery for their propulsion.

THE SOUTH WALES INSTITUTE OF ENGINEERS.

April 26.-The third annual meeting was held in Newport last Tuesday, under the presidency of Ebenezer Rogers, Esq., F.G.S., &c. There were present a considerable number of scientific gentlemen engaged in the various industries of the district. The Mayor of Newport and other gentlemen of the town were also present as visitors. By a regulation of the institute we are unable to give a report of the proceedings; but we learn from the Star of Gwent that the discussion chietly turned on the combustion of coal, in the course of which the comparative values of English and Welsh coals were discussed-the opinion of the members being adverse to the merits of English coal for steam purposes. A paper by Mr. Wilson, of Sheffield, on Steel Manufacture brought out the fact that the trade had been materially stimulated by the demand for crinoline hoops. The discussion of this paper was postponed to the next meeting. A paper by Mr. Murphy, of Newport, on Railway Wheels was also postponed, on account of want of time for its reading and discussion. The dinner was held at the Westgate Hotel at half-past four o'clock. The chair was occupied by Ebenezer Rogers, Esq., FG.S., president, supported by H. Sheppard, Esq., Mayor of Newport, Sir T. Phillips, F. Levick, Esq., Blaena, Warrington Smyth, Esq., &c. The vicechair was filled by W. S. Clark, Esq., of Aberdare. About eighty gentlemen were present, including those who were not members of the institute, but who were interested in its welfare.

MANCHESTER LITERARY AND PHILOSOPHICAL

SOCIETY.

SOCIETY OF ARTS.

May 4.-Mr Leonard Wray read a paper on Timber for Shipbuilding. A report of this lecture will appear in our next number.

MEETINGS FOR THE ENSUING WEEK.
Mox.-London Inst., "On Commercial Law," by G. W.
Hastings, Esq., at 8 p.m.

Geographical Society-1., "Notes on the Lower
Danube," by Major Stokes, R.E., communicated
by Captain Collinson, R.N.; II., "Observations
on the Geography of Central Africa," by James
McQueen, Esq., F.R.G.S.; III., "Remarks on
the Seychelles," by Lyon McLeod, Esq.,

F.R.G.S., at 8 30 p.m.

TUES.-Royal Inst., "On the general facts and leading
principles of Geological Science," by J. Morris,
Esq., F.G.S., at 3 p.m.

Inst. Civil Engineers-I., Discussion upon Mr.
Kingsbury's paper "On the Victoria Docks," and
upon Mr. Harrison's paper "On the Tyne
Docks;" II., "Short account of the Wrought-
iron Girder Bridge over the Spey, on the Aber-
deen and Montrose Railway,' by Mr. W.
Fairbairn, M. Inst, C.E.; III., "Description of the
Government Water-works, Trafalgar-square, by

Mr. C. E. Amos, M. Inst., at 8 p.m.
Zoological, at 9.

WED.-Society of Arts, "On the Recognition of Music
among the Arts," by Mr. Henry F. Chorley, at
8 p.m.

THUR.-Chemical, at 8 p.m.

Society of Antiquaries at 8 p.m.

THEORY OF NAVAL ARCHITECTURE.

No. VII.

IN the two preceding articles we have shown where ordinates should be drawn in a curvilinear figure, to give a tolerably correct approximation to the area. As the examples there taken are of the same character as ordinary midship sections, it will be seen to be necessary, when operating upon the draught of a ship, to place the ordinates closer in the neighbourhood of the keel, than in the other portions. Again, all ships, except those designed for high speeds, have the greatest amount of curvature in their horizontal sections at their extremities; consequently, when placing the ordinates to calculate the areas of these sections, it will be necessary to put them closer at the extremities than in the other parts.

We must now hasten to apply the rules to the calculations of the displacement of a ship, reserving all further discussion of the relation between the ordinates and areas until it is required from the nature of the calculations.

Our first example will be the simplest case which can be given, namely, a ship in which the constructed load-water line is parallel to the keel,

Royal Inst., "On the Seven periods of Art," by and iron is the material of which she is composed.
Henry Layard, Esq., at 3 p.m.
Linnean, at 8 p.m.

FRID.-United Service Inst., "On the history of Gun-
locks," by Mr. Robert Pritchett, at 3 p.m.
Royal Inst., "On the changes of terrestrial tem-

perature at different geological epochs," by W.
Hopkins, Esq., M.A., F.R.S.
SAT.-Royal Inst., "On Modern Italian Literature," by J.
P. Lacaita, Esq., at 3 p.m.

EXPLOSIONS AT GUNPOWDER WORKS. TO THE EDITORS OF THE "MECHANICS' MAGAZINE." April 19.-W. Fairbairn, F.R.S., President, in GENTLEMEN, Every question has its "pro" as the chair. The following gentlemen were elected well as its "con," and the question of gunpowder members of the Society: As honorary members: works and their owners is no exception to the rule. W. J. Macquorn Rankine, LL.D., F.R.S., &c.; Baron In your last number are some rather severe strictures Carl T. von Reichenbach. As ordinary members: which I think need some reply. With the disgrace T. H eelis, T. R. Wilkinson, A. Ransome, B.A., M.B., reflected upon chemical progress, I have now nothing M.R.C.S. The annual report was then read by Dr. to do, but think I can prove that powder manufacSchunck, one of the secretaries. In their report the turers are not quite so insensible to improvement as council express their conviction, that at no period of you seem to imagine. Has nothing been done (say its existence has the Society been in a more flourish- during the last 25 years) towards improving the maing condition. It has been considered advisable to chinery necessary for the manufacture of gunpowder? postpone the preparation of a new catalogue of the Has no improvement been made in "1 "Mixing-houses ?" library until the result of a correspondence now in Has nothing been done towards improving the "Inprogress with a great number of scientific societies corporating Mills?" Are the "Press-house," the and institutions, for the purpose of introducing a Caming-house," the "Drying-house," the" Dustingmutual exchange of publications, shall be known, and house," what they were thirty years ago? These the system of such exchanges shall thus have been changes, I confess, are not blazed abroad to the world; more completely developed. The library is gradually but every one conversant (and very few are) with the emerging out of the insignificance in which it had manufacture of powder knows that the number of remained until within the last few years. The im- hands requisite in the houses is greatly diminished, provement is almost entirely owing to the exchanges and that the risk to which these are exposed is also referred to; but an improvement on that basis, to greatly diminished. Surely you will not grudge the whatever extent it be carried, can never bring the manufacturers their due meed of praise for these imlibrary to a desirable state of completeness. The provements-improvements the carrying out of transactions and other publications of learned which has cost large sums of money, but all has been societies and institutions, which are thus obtained, cheerfully done where any good was likely to be atare undoubtedly of the greatest value, and of course tained. I cannot account for the lowness of wages absolutely necessary in a scientific library; but still, given to men employed in powder works, and would they constitute only one of its chief elements. fain hope there is some misinformation upon the matScientific periodicals and separately printed works-ter; but I can say that all do not pay so badly as is the other elements-must, as a rule, he bought. A represented. At the largest manufactory in England project for supplying the necessary funds has been (perhaps in the world) the men employed in the more submitted to the council, and, if approved of, will no dangerous parts of the business earn weekly from 35s. doubt be recommended to the attention of the to 44s., and with pride I acknowledge that a case of members. After some remarks by Mr. Chadwick, drunkenness is never known; and never does a man the report was adopted on the proposal of Mr. Curtis, (and there is a great number) ever stay from work seconded by Dr. Clay. The annual election of officers unless from sickness. Give men good wages and you then took place, when the following gentlemen were may generally get good men. At the factory aboveelected-President: W. Fairbairn, F.R.S., Vice- mentioned not a fatal accident has occurred for more Presidents: J. Prescott Joule, LL.D., F.R.S., F.C.S; T. than twenty years. True, every care is taken both in Hopkins, M. Brit. Met. Soc.; Joseph Cheeseborough the choice of men and machinery, but if, as is thought, Dyer; Robert Angus Smith, Ph.D., F.R.S., F.C.S. these accidents are attributable to the state of the atSecretaries: Edward Schunck, Ph.D., F.R.S.; mosphere, who shall cast censure upon the unfortuRichard Copley Christie, M.A. Treasurer: Henry nate manufacturer because he cannot cope with the Mere Ormerod. Librarian: Charles Fredrik Ekman, elements? Of the Council: Rev. Wm. Gaskell, M.A.; Richard Roberts, M. Inst. C.E.; Joseph Baxendell, F.R.A.S.; Edward William Binney, F.R.S., F.G.S.; Peter Spence; Joseph Atkinson Ransome, M.R.C.S. Mr. Dyer moved, and Dr. Joule seconded, a vote of thanks o Mr. Ekman, the librarian, for the valuable services endered by him to the Society. The meeting was hen adjourned to Tuesday the 3rd of May.

Pray permit the subject to be fully discussed in your valuable journal, especially any information respecting the state of the atmosphere at the times of explosions. The lives of many depend upon this business, and if anything should be discovered by which these lives may be preserved, blessings will ret on the head of the discoverer. I am, &c., POLVORA,

In this case the sections of the ship can be chosen so as to introduce no appendages which may not be safely neglected; the calculations will therefore be direct. The length of this ship between the perpendiculars is 156 feet; breadth extreme, 20 feet; depth, from the upper part of beam to lower part of the keel, 11 feet 6 inches; burthen, builders' measurement, 310 tons; draught of water forward and aft, 6 feet 6 inches; keel below the lower edge of rabbet, 6 inches.

Let Fig. 14 represent the sheer draught of a screw ship; L WL, the constructed load-water line; the length of the part CD between the stem and the foremost stern post is 151.2 feet. Divide CD into twelve equal portions of 12.6 feet each; through the points of division let vertical transverse sections be drawn; these are represented by the vertical straight lines 1, 2, 3, &c., and in order to meet the greater curvature, usual in ships at their extremities, let sections 1, 2, between 1 and 2, 2 and 3, 11 and 12, 12 and 13 11, and 12 be drawn parallel to these midway respectively.

Again, the depth from the load-water section to the intersection of the side of the keel and the curved surface of the ship is 6 feet; let this depth be divided into four equal portions, each of which is 15 feet, and at the points of division let the water sections 2 WL, 3 WL, and 4 WL, be drawn parallel to the load-water section; and to meet the greater curvature in the neighbourhood of the keel let the sections 3 WL, and 4 WL be drawn parallel to these midway between 3 WL and 4 WL, and 4 WL and 5 WL, re. spectively. All these sections are represented in the sheer plan by horizontal lines.

The plane, LWL, of the load-water line-the transverse vertical plane through (1), the after part of the stem-and the plane through the middle line of ship, all at right angles to each other, are taken as the co-ordinate planes.

Now, it is evident that the transverse vertical planes intersect each of the horizontal or water sections, in lines perpendicular to the longitudinal plane through the middle of the ship, and therefore perpendicular to the middle line; consequently, the intersections of each horizontal section by the transverse sections may be regarded as ordinates to the curve in which that horizontal plane cuts the ship. Also since the vertical sections 1, 14, 2, 2, and 3; 13, 121, 12, 114, and 11, are drawn at 63 feet apart, the corresponding ordinates of the horizontal sections are 63 feet apart, and the number in each case is odd, therefore the area of these parts may be found by Rule 2. Also the ordinates between sections 3 and 11 are 12.6 feet apart, and the number is odd, therefore the whole area of any horizontal section may be found as has been already described.

MESSRS. HALL AND WELLS IMPROVED ELECTRIC TELEGRAPH CABLES.