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Atted with iron-wire standing rigging and more than is naturally due to it; and lightning conductors in her Majesty's 3rdly, that such substance may contain navy by Mr. Smith, and that fourteen less than its natural quantity by a portion other additional naval ships have been having been removed. The first state fitted with wire-rope lightning conduc has been called “ latent," the second tors, besides twelve steam ships and ves “ positive," and the third " negative." sels for various companies in the English The positive and negative electrical merchant service during the last seven states appear to be produced from any years, as also some for the Russian and cause of disturbance sufficient to destroy other governments.

the molecular attraction of matter when I am also informed that orders are now two or more elements are in operation, given for fitting thirty sail of the line and any change, such as chemical action, with lightning conductors on the most is taking place. Electricity is evolved efficacious and certain principle; there. by liquids passing into a solid state, as also fore the subject appears to be considered by the liquefaction of solids, and the proof vast importance and deserving the duction and condensation of vapours from most powerful investigation : I will there- liquids holding either acids or salts in fore hazard a few additional remarks solution. Hence the sea produces amaz. more with a view to elicit useful and ing quantities, which is probably the practical facts from others than from any cause of a clear atmosphere being gene. idea that such can possibly result from rally positively charged-of contrary curmyself.

rents of wind, accompanied by humidityThe devastating effects of storms and and of any other change that may take tempests, supposed by many to be of place in atmospherical matter. The electrical origin, which have within the earth, ocean, atmosphere and clouds, may last few weeks sent so many valuable therefore become charged by their naseamen to their last account, besides the tural operations on each other, one part destruction of a vast amount of property, or district positively, and the other nemake the inquiry into the most certain gatively; and although it is said that the means of preventing the injurious effects earth and sea are often in the positive of lightning at the present moment condition, I am of opinion, from repeated doubly interesting, particularly as the observations of lightning, that the positive stern face of winter is so near us.

state generally exists in the clouds wbea I observe a lecture has lately been de the earth and atmosphere are in contrary, livered by Lieut. Sabeen, R. N., at states, though probably the electricity of Plymouth, on the subject, embracing all the earth and sea is frequently in a passive the prominent considerations of lightning- state, whilst the most violent commotion conductors, drawing a comparison be of electrical discharges is going on between the plan projected by Mr. Snow tween the clouds. But the inatter under Harris and that practised by Mr. Smith, enquiry being when the sea and clouds are and arriving at a conclusion decidedly in in opposite states, I will confine my obfavour of the latter.

servations to that consideration, only obIn order that your readers may be serving, that these are general sugges• able to judge for then selves I will, as tions, details being foreign to my purpose. briefly as possible, point out the object to be attained, and the means proposed to be aggregated in a highly

Suppose several square miles of clouds and adopted by Mr. Harris and Mr. dition, and to be drifted by currents of Smith for its accomplishment. The sub wind towards a fleet of ships

, and that ject of aërial or atmospheric electricity the ocean in the immediate vicinity of the has been so fully speculated and theo vessels is in the opposite electrical state, rized on, that I presume it is generally should the approach of the supposed to consist of three different only a little more than is equal to the conditions ; Ist

, that the electric fluid Striking distance of the redundant elecsurrounds' and pervades every subo tricity, it can easily be imagined that the stance in nature with which we are tall masts of a vessel interposing belween acquainted in a quiescent or latent state, the clouds and water would form a me. without affording the least sign of its dium of communication, although the existence ; 2nd, that any body or substance may contain and be surrounded by resistance would prevent a discharge

distance might be such that the aërial

without some such intervening or con masts; but would, nevertheless, be parducting power.

ticularly applicable to the bolts by which The direction of a concentrated mass the electricity has to find its way out of electric fluid when seen in the air is, of the hold to the water. Bolts used in I believe, almost always in straight lines, framing the ship, I apprehend, are in viz., taking the shortest path to the point all cases driven in, and completely fill where its presence is required to restore the holes: there can be no yielding, equilibrium; nor is the apparent zig-zag either in wood or metal, in this case, and lightning an exception, because, although therefore the contact may be presumed to angular paths are formed, the cause of be perfect; but I do not consider that such appearances would be the vicinity of even this has been the primary cause of the detached masses of clouds having their disruption of the frame-timbers spoken attractive and repellent forces in different of as having occurred to Mr. Harris's directions as seen by the eye. I will plan, but should rather be inclined to astherefore proceed to enquire what is the cribe it to the absence of a perfect contibest means of constructing the conductors nuity of the slips of copper forming the confor ships which shall possess the greatest ducing material, and the bolts intended to facility for the transmission of the electric transmit it to the water. A much stronger fluid from the top of the mast to the objection may be stated to take place at water, in the most direct manner, and the junction of the pieces of metal for which, at the same time, shall not pro want of perfect contact. Dr. Priestley duce any obstruction or inconvenience to found that a considerable weight was the seamen ?

necessary to bring the links of a chain in Mr. Harris's proposition is to let such a state of contact as to prevent devertical slips of copper, about 2 inches composition of part of the metal, in wide, into the surface of the mast, to be conducting electrical discharges by it; fastened by nails, making the surface of besides which, other experiments have the mast flush and even. These slips of proved that bringing metals to touch copper to extend froin the top of the does not produce perfect electrical conupper mast down through the deck and tact, but that considerable pressure is hold to the kelson, and where, if I un necessary. The entire height of the derstand Lieutenant Sabeen's description, mists of a first. rate war-ship being from it ceases; having, in fact, brought the 150 to 200 feet, and the slips of copper lightning into the hold of the ship, it being, say 4 feet, there would be froin has to find its own way out by the bolt of forty to fifty partial interruptions by the the frame work in the best manner it “bütt joinis" in addition to those at the can. Lieut. Sabeen raises an objection to caps, cross-trees, and decks in a lateral letting in the slips of copper, inasmuch as direction. It has also been discovered in its contact on the inside and edges leaves very carefully conducted experiments, that only the outside surface free for the con meials are shortened by powerful disducting operation. I do not consider this charges of electricity being sent through a very forcible objection. It is not them, which would sensibly increase the possible, from the very nature of the evil, though if long lapped joints were inwork, that à carpenter can let in, and troduced, it would be obviated. The uppe fix a copper plate with such extreme and masts and guns of a ship having to be so perfect contact, as not to leave sufficient frequenily removed and replaced in uncerspace for the passage of a subtle fluid, tain weather by the seamen, when neither which, in such a case, is not supposed time nor talent is sufficient to ensure perto require any; and, indeed, if it were so, fect contact, and under circumstances the objection is nearly as applicable to too, when, of all others it is most rethe wire rope, as to the slips of copper; quired, appears to me a strong argument for the minute spaces formed by the tan- against the use of rigid plates or strips of gential contact of the wires, would be metal, for such an important purpose; almost as impermeable to the passage of but the greatest absurdity of all is, that electricity, as the partial contact of the of bringing the most instantaneously de. slips of copper in tlie grains of ihe wood; structive element into the hold of the therefore, I consider the objection is ship, and making no other than a "bequite gratuitous wlien applied to the wildering" process for its escape. Not

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much less reprehensible would have been plate let into the ship's side, until it the conduct of the builder of St. Martin's reaches the lower edge of the upper tier church (the accident to which, arising from of copper sheathing, where it ceases. carelessness, will be remembered by all By this simple use and arrangement of your readers,) bad he brought the con a copper wire rope every necessary conductor from the top of the tower into the dition is complied with, and the ease and sacramental plate chest, and from thence facility with which a flexible rope may to the earth let it follow its own capri be made continuous by knots, splices, and cious fancy.

other means must be obvious to every one The question of suitability having been under every circumstance to which a considered, I will now speak of the cost. ship is exposed. The consequence of From the close observation of unquestion such simplicity is, that it can be applied able authority, it appears that the various in a very short time, two days, I am operations of letting in and fixing the cop- informed, being sufficient to protect a first per slips, making all the necessary bends class ship of war, and the expense of and junctions at the heads of the masts, which does not exceed 60l. In the event decks, and hold, occupy a period of three of its being desired to transfer a set from weeks; and that the cost, in the few in- one ship to another, the materials are in stances in which it has been applied, has no way injured or rendered unfit; and in been from 4001. to 5001. Three weeks making alterations, the usual knowledge so occupied, under the ordinarily judicious possessed by seamen will be equal to the regulations of our naval service, would task; and at all times, the materials formprobably be of as little consequence as ing these conductors, when removed, will the above sum taken from our Treasury, be worth two-thirds the first cost. provided the work were worth it; but such These important considerations of does not appear to be the case. Both, cheapness and facility with which it can however, must be weighty objections to be applied, bring it within the reach of the proprietors of small trading craft; all owners of vessels, who will doubtless to which we must add, the injury to eventually appreciate the value and avail masts and spars by letting in and punc themselves of the benefit. turing, by holding the water and thereby Mr. Smith's Pamphlet contains many occasioning decay; as also the impossibi. most favourable certificates from naval lity almost of transferring the materials officers, masters of merchant vessels, and from one ship to another; or, in the case others of nautical experience; and I of masts and spars being carried away or have also seen certificates which have not left unprotected, the labour of fixing been published, the whole of which form which probably amounts to four-fifths of an additional link in the chain of evidence the entire cost.

of its superiority over all other methods It only now remains for me to speak of the plan so successfully practised by No: being fully acquainted with the Mr. Smith, and which, from its extreme copper works” of a ship, I do not see simplicity, the facility with which it is ap why the wire rope used at the topmast plied, the certainty of its usefulness, and saould be of less diameter than the lower small cost, renders but few words neces set; as far as the transit of lightning is sary. I know of no instance amongst the concerned it would appear that a rope numerous beneficial measures adopted by of uninterrupted and uniform diameter the present enlightened Government of would be preferable; and if it were altothis country, in which a more judicious gether increased from three-eighths to and sound discretion has been evinced half inch, or five-eighths in diameter, it than in the adoption of Smith's Light would be still better adapted for the conning Conductor. It contains all that is duction of large quantities of electricity. necessary and nothing further. A cop In the hope that these remarks may be per wire rope is tinned over and fastened sufficiently interesting to appear in your

cap of the topmast and is led columns. down by the side of the masts to the cross I remain, Sir, yours respectfully, trees, where it is fastened to a slip cop

J. R. HILL per hook, and thence conveyed down 98, Chancery Lane, Dec. 12, 1842. the after shroud and shackled to a copper

in usc

on the

No. of

square inch


“ Thus, then, it follows, that the strongest

form of section in a cast-iron beam is that Rolls' Court, Chancery-lane, Wednesday, by which the material is collected into two Dec. 21.

unequal flanges, joined by a rib, the greater

flange being on the extended side ; and the Baker v. Cole.

proportion of this inequality of the flanges Mr. Dixon, for the plaintiff, William Ba

being just such as to make up for the ineker, moved ex parte for an injunction to

quality of the resistances of the material to restrain the defendant, Richard Cole, from

rupture by extension and compression reusing the trade-mark or name of “ Impilia”

spectively. Mr. Hodgkinson, to whom this upon the sole of any boots or shoes sold by

suggestion is due, has directed a series of him, or by his direction, and from selling

experiments to the determination of that any boots or shoes with that trade-mark or

proportion of the flanges by which the name thereon, or any boots or shoes made

strongest form of section is obtained. The according to the plaintiff's patent.

details of these experiments are found in the

The plaintiff's affidavit stated that he had disco

following table :-
vered a new and useful invention for an im-
provement in the manufacture of boots and
shoes, for which, in January last, he had

Area of
Ratio of the
whole section

Strength per obtained a patent, and had, in July, enrolled

section of the his specification. The invention was speci.


in square

of section. fied to be “ the applying a piece or sole of matted or felted horse or other strong curled hair between the inner and outer sole of the boot or shoe.” The plaintiff had designated

1 1 to l. 2.82 2368 the articles thus made by the name of “ Im

2 1 to 2

2.87 2567 pilia,” which name had become universally

3 1 to 4

3.02 2737 known as designating his boots, and never

1 to 4.5


3183 had been before so used; but he had caused 5 1 to 5.5 5.0

3346 it to be adopted as the trade-mark of the

6 1 to 6:1 6.4

4075 boots and shoes made according to his patent. He discovered on the 17th instant, that the defendant was selling boots and shoes which

“ In the first five experiments, each beam he represented to be “ Impilia" boots, &c.,

broke, by the tearing asunder of the lower made according to the plaintiff's patent, ex

flange; the distribution by which both were cepting that instead of horse-bair there was

about to yield together-that is, the strongwool placed between the soles. The defend.

est distribution-was not, therefore, up to ant had sold to a man of the name of Wise

that period, reached. At length, however, a pair of these boots, with the word “ Im

in the last experiment, the beam yielded by pilia' upon the outer sole.

the compression of the upper flange. In Injunction granted.

this experiment, therefore, the upper flange was the weakest ; in the one before it, the lower flange was the weakest. For a form between the two, therefore, the flanges were of equal strength to resist extension and

compression respectively, and this was the MOSELEY'S MECHANICAL PRINCIPLES

strongest form of section.

In this strongest

form, the lower flange had six times the maENGINEERING AND ARCHITECTURE.

terial of the upper. It is represented in the CONCLUDING NOTICE.

accompanying figure. The theory of rupture by transverse strain is illustrated by a new class of problems, having reference to the forms of beams with wide flanges, connected by slender ribs, which will be found fraught with useful practical instruction. But here, again, the reader will not fail to be forcibly struck with the subordinate part which the mathema

" In the best form of cast-iron beam or tician plays, compared with the experi girder used before these experiments, there menter. For example :

was never attained a strength of more than


2885 lbs. per square inch of section. There (yet very imperfect) examination of this gewas, therefore, by this form, a gain of

nerally most valuable work to a close ; but 1190 lbs. per square inch of the section, or of gths the strength of the beam.”—Page

before doing so, we must advert briefly to 558.

what we consider its chief defects. It is only in the case of cast-iron beams In the first place, we must state our strong that it is customary, by varying the form of impression, that it is by far too learned for the section, to effect a saving of material ; the classes (Engineers and Architects) for but Mr. Moseley sees no reason, as neither whose use it is specially designed. To be do we, why the same principle of economy

read and understood with ease, it requires should not be equally applicable to beams of that the reader should be master of all the wood.

arts and even refinements of mathematical The following general enunciation, by the analysis, and that is more, we fancy, than Professor, of the conditions requisite to the one in ten of the respectable classes (excel. production of a “solid of the strongest form, lent practical men, notwithstanding) can with a given quantity of material,” is one of pretend to be. the happiest, because clearest and most in. In the second place, the learning is not telligible, in the whole work.

seldom of rather a superfluous character ; “ The strongest form which can be given showing, it may be, great proficiency and to a solid body, in the formation of which a skill on the part of the author, but calculated given quantity of material is to be used, and

to be of no practical service. to which the strain is to be applied under

And, in the third place, the anthor, in his given circumstances, is that form which renders it equally liable to rupture at every

fondness for theorizing, forgets, occasionpoint ; so that when, by increasing the strain ally, how essential it is to every sound to its utmost limit, the solid is brought into theory, that it should be based on facts. the state bordering upon rupture at one point, it may be in the state bordering upon

We may cite, as a striking example of all rupture at every other point. For, let it be

these three defects, the whole of the section supposed to be constructed of any other on that very simple and useful agent in maform, so that rupture may be about to chinery, the band. Every mechanic knows take place at one point when it is not about

that the best arrangement for communicatto take place at another point, then may a portion of the material evidently be removed

ing the motion of one shaft to another from the first point, without placing the solid through the medium of a band and drums, there in the state bordering upon rupture, is to apply the moving and working pres. and added at the second point, so as to take it out of the state bordering upon rupture at

sures on the same side of a vertical line passthat point ; and thus the solid, being no

ing through the axes of the two drums: every longer in the state bordering upon rupture

mechanic knows too, that a band is worked to at any point, may be made to bear a strain most effect when the two portions of the band greater than that which was before upon the

between the drums are made to cross one anpoint of breaking it, and will hare been ren. dered stronger than it was before. The first

other. Neither can any mechanic of common form was not, therefore, the strongest form intelligence be at any loss for the causes of of which it could have been constructed with both results-namely, the parallelism of the the given quantity of material; nor is any

pressures in the one case, and the greater porform the strongest, which does not satisfy the condition of an equal liability to rupture

tion of each drum embraced in the other. at every point.

Effects and causes so well known, and so ob. “ The solid constructed of the strongest vious as these, might, with propriety, hare form with a given quantity of a given ma. been disposed of by a simple en unciation ; terial, so as to be of a given strength under a given strain, is evidently that which can be

but our very learned Professor must needs de constructed of the same strength with the

monstrate them mathematically, and in doing least material; so that the strongest form is so puts one forcibly in mind of Swist's de. also the form of the greatest economy of finition of this sort of scholastic accomplishmaterial.'_Page 533.

ment_namely, that it is “the putting We must now bring our rather extended

number of queer looking things through a

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