it, and by placing the weight in the cask upon the portion of the hoop we have reserved, we obtain nearly all the cohesive force of the iron. The weight applied upon the beam will endeavour to distend the beam, and to force down the camber given it when screwed up by the nuts. In forcing the beam down, the weight laid upon it will endeavour to distend the arc or hoop at the ends against the nuts; but the hoops now oppose their cohesive force or power to sustain the weight. In many experiments which we have tried, to ascertain the ultimate weight a beam so constructed would bear, we have proceeded as far as the ultimate practicable force of the cohesive power should be applied. We have frequently shown an experiment with two small pieces of wood and iron, which toge ther and separately would have carried, for all useful purposes, about half a hundred weight; but when combined in the manner here described, have carried, without any injury to their tensile power, the load of six hundred weight; evidently and entirely de pending upon our peculiar mode of mechanical structure. There can be no hesitation in concluding that if this subsidiary plan be added to the construction of beams, we shall thus obtain a power to sustain a load which will produce very great advantage and economy.

"In some ordinary constructions we have sustained well and permanently from fifteen to thirty times the weight which the same materials could have borne in the common mode of forming beams, &c. These advantages, therefore, must not be lost sight of, when we consider, that rails, viaducts, bridges, roofs, floors, beams, spars, rafters, joists, galleries for churches, chapels, theatres, ships' masts, decks, ribs, &c. will all, with a variety of other purposes, admit of the aid this principle lays down; we may cunclude, that much benefit must accrue, and superior strength be given, at a much lighter expense thau can be obtained by any other mode of construction. We have devised a rule to calculate both the dimensions of the chord or beam, as well as the size of the segmental hoops, founded upon many and various experiments, undertaken with great care, and conducted by accurate observations, not only by ourselves, but aided by some practical and scientific friends; the result has thrown new light upon this branch of mechanical science, varying greatly from what would have been the supposed result, and fully bearing out the statement relative to carrying the weight we have previously named.

"There is another feature in this plan that we have not touched upon. From the effect the application of the segmental hoop has upon the beam, it is clear there can be no outward pressure upon the supports; the

walls of a building cannot be oppressed with any outward thrust, as in the case of com. mon beams, the whole superineumbent weight being confined and bound up in the beam. We shall see this more particularly exemplified when we come to treat upon bridges here we may remark, that the walls do not need to be constructed so stoutly as in ordinary buildings. The strength required being that they should support themselves and any perpendicular weights placed upon them, by such beams; since our beams simply press or rest upon the walls, in a vertical position (not exerting any lateral thrust), which will effect some considerable saving in the outlay thus this beam will likewise give greater safety to buildings, for if the weight be placed upon the walls, it will be more securely supported than by the weight pushing outward or against the walls, which in a great measure is done by the ordinary beam."

We shall now quote Mr. Booth's exposition of the methods and advantages of applying the two principles, together and separately, to various constructions:

"Bridges.-Fig. 4 represents a bridge, constructed according to the improved plans for beams; A A is a laminated beam, which forms the balustrade, with an ornamental railing at the top; B B is one of the seg mental hoops secured to the ends of the beam AA; DD are pillars or piers; E E the roadway. Having described the figure in this cursory manner, we proceed to show the strength of the materials for such a construetion, taking certain dimensions calculated for practical purposes. Suppose it be required to erect a bridge, 30 feet span, 12 feet wide, to carry 10 tons; by the common principles of calculation we find a plate of wrought-iron (for we shall use boiler plates,) 30 feet long, nearly 1 inch wide and 24 inches deep, placed edgewise, will carry 10 tons. Let this plate be divided into four plates, in its longitudinal direction, we thus shall have four plates, each 30 feet long, 0.25 inches wide, and 24 inches deep, a little extra length must be allowed for bearings, say 18 inches at each end. These plates may be made out of a number of lesser or shorter plates; let each be 6 feet long, and rivetted to the succeeding plate, in the usual manner of fastening boiler plates together, except that the pins or rivets need not be so numerous, about ten rivets to each plate will suffice. Having done this, we will take two plates, one on each side, to form one balustrade of the whole length of the bridge, fastening them to each other, side by side, with screws, bolts, or pins, upon the lamellar principle, and placing at intervals between them (where the pins perforate the sides), blocks of wood, so as to keep each plate at the distance of 4 or 6 inches from

each other. Let them now be closely screwed up, being firmly fixed upon the walls or piers: a stone or cast-iron cap at the top of the pillar will form the bearing for the bridge. Upon this laminated beam, must be placed a sill of wood or iron, upon which also any kind of ornamental work may be affixed, as a surmounting finish. We now proceed to notice, in the next place, the mode of making the roadway, which must be subtended from the sides, or have laminated beams across the bridge from one side to the other; this is effected by affixing a piece of iron, inch thick and 2 inches wide, in a line with the rivets from the top to the bottom of the laminated sides, and underneath the rivets fastened on with them or screwed on by the same pins, &c. that fasten the two pieces of the laminated sides and blocks together. This piece must descend below the bottom of the sides, and be returned inward, forming a right angle at the bottom for the oak or iron beam to rest upon, which stretches from side to side, and which beam forms a' chord line, with a segmental hoop going across the road, the hoop is then affixed underneath the beam, passing through the sides of the laminated beam and upright bar, and screwed on the outside with proper washers fitted underneath the nuts, so as to make the screws at right angles with, the nuts: thus, then, the two sides will be connected and bound together by this beam of wood or iron. The segmental hoops may be varied in number according to the mode intended to cover the roadway. If one were placed every 6 feet, then five such beams would suffice; which might be overlaid by oak planks of 3 inches thick, 5 feet long, or by iron net-work having a superstratum of macadamised stone; thus a strong covering would be made for the roadway."

Railway-bars. After some remarks upon the controversy between Professor Barlow and Lieutenant Lecount upon this subject, Mr. Booth proceeds to state Mr. Wirty's plan:

"We purpose to divide the 1.25 inches of Liron into four parts, longitudinally, or in the direction of its length; or to take 2 plates Teach 25 inches, and two others 375 inches, placing between these laminæ of iron, 3 pieces of oak of equal lengths with them, 412 inches in thickness, thus forming a rail 2:5 Linches wide. Considering the bearings to be 14 feet as before, the oak itself will carry 1718lbs. which, if added to 6875lbs. 8593lbs. carried by this rail, being double the weight >carried by the common rail, as before-named, yet having the same weight of iron only. If, as on the Manchester and Liverpool line, rails of 60lbs. per yard carry 5 feet, these will carry 9 or 10 feet, and in a distance of 50 feet the saving in blocks would be 5. Now,

2

look at it in another shape. If the blocks are put every 5 feet, then one-half the strength of the iron lamina, with a proportionate increase in the strength of the oak, will give all the strength or power wanted, by taking 30lbs. of iron in lieu of 60lbs. to the yard. Nevertheless, we cannot suffer to escape the opportunity of making a further saving. Hitherto we have confined ourselves to the law laid down for certain dimensions, in the depth of the rails; did we see any just reason why these should be closely followed, we might stop there. Let us avail ourselves in every point, with our advantage over every other plan. Let the rails be made double the ordinary depth, reserving the same quantity of iron, but making it half the thickness, we shall then be enabled to carry double the weight; and keep the rails of the same width, by increasing the width of the oak as much as we decrease the width of the iron; if the blocks be only 4 feet asunder, we shall now carry 17,186lbs. per yard, but as it is only needful to carry 4134lbs., we have strength enough to place the blocks 16 feet asunder; and if the bearings, as in some instances, are placed 6 feet asunder, 20 feet may be the distance, thus saving 7 blocks out of 10, and gaining this superior strength. It is perfectly understood, that the lamina of wood and iron shall be screwed or bolted together at proper intervals, in parts where the bearings shall be great; we purpose also that rods should extend from one rail across the tram-road to strengthen and keep parallel the opposite rail; being screwed or bolted on each side of each rail, to hinder any lateral deflection; the bars so used are subjected only to a longitudinal pull, and require to be of small thickness.

"Viaducts, comprising Rail and Railway in one Construction.-Upon referring to fig. 5, will be seen a railway similarly constructed to the rail we have been treating upon, varying only in its dimensions or depth. In that part of the road where it rests upon the embankment D, the rail A is formed of the ordinary dimensions, 24 inches wide, 5 inches deep, and laminated with alternate pieces of wood and iron; BB are the other two lamimated rails of greater depth than A, having to cross the valley CC; these rest upon the pillars GGG.-FF are segmental hoops, used as before described, being screwed at the ends or sides of the laminated rails BB. These lamina may be disposed to comprise two objects, either to be the rails themselves, or to be beams for the support of the rails, and combined with them.

"Let us suppose a viaduct and railway requiring 9 arches, each arch to be 50 feet span. Instead of proceeding in the common mode, similarly to the viaduct across the Sankey

"Roofs and Floors.-Fig. 6 represents a roof made according to this improved me thod; AA are two principal spars, so called because they are made stronger than the other spars, calculated to bear according to the weight to be carried, and generally about double the depth of the other spars; these are seen in the drawing, with the segmental hoop attached to them, and the stays as before described. The purlins B B are made in like manner, and stretch from one principal spar to another, which are placed at proper intervals in the roof, say about every eleventh; the stays underneath these purlins are fixed with most advantage underneath each spar. In some cases we have found that instead of a piece of timber (the present purlin) stretching from one principal spar to another principal spar, short pieces of wood of the same dimensions as the spars themselves are quite sufficient from spar to spar, i.e. between each spar. The stay-pieces in this case must be direct against and underneath the spars, with their feet resting upon the segmental hoop. Some little timber is thus saved, and an opportunity afforded for using up the small pieces that are always to be found about a building, CC are rods of iron carried across the building at the foot of the roof, and through each wall-plate to tie the roof togetheir, their longitudinal pull being calculated at about 6 tons per square inch.

"It will be evident, that by such arrangements the main-beam, king-posts, and other cumbrous appendages in ordinary roofs, may be wholly dispensed with. There will be found power sufficient to carry any weight, whether the roof be of slate, tiles, lead, or iron. The dimensions of the spars need only be sufficiently wide to give space to drive the nails without fear of splitting them; all other purposes for bearing weight being supplied by the segmental hoops. We beg to refer our readers to our drawings and calculations upon roofs, the mode of fitting up the spars, hoops, &c. they will be found most simple and effective. All questions required, in order that these particulars may be furnished at any time, may be summed up as follows, viz.:

"1. The length and thickness of the wallplate or of the building.

"2. The leugth of the spar and the width of the building.

"3. Whether to be covered with tiles or slates,

"Fig. 7 will lead us to the plan for fitting up floors; this mode consists of two parts, differing much in their manner, but producing the same result; the one adopting part of the present system to procure the same appearances in a room as by common construction; the other a novel invention, thereby giving scope for further improvement, and out of the common wearied and beaten track of centuries for constructing ceilings. Great ornamental effect, combined with great simplicity, may be produced at much less expense than by lath and plaster ceilings. AA are the walls of the building; BB, the joists; CC, the segmental hoop carried through and underneath the joints; DD, the floor. In looking into the nature of such constructions, the following may be seen as some of the advantages to gain superior strength, and the mode of applying this patent. Suppose a floor 20 feet square is to be laid, let the spars be placed at the usual distances of 1 foot 6 inches from each other, let them be 5 inches deep, but of such a width, that, with the assistance of the seg mental hoops, they may bear an equal burden in all parts of the floor; the hoops shall be placed every 5 feet asunder, thus requiring three hoops of very slight width and thick ness, having their ends passing through the walls, or placed within them. If this floor had been made upon the ordinary plan for common purposes, spars 11 inch x 3 inch x 20 feet must have been used; the difference in timber, therefore, is manifest, while the extra expense of some 1 cwt. or 1 cwt. of iron will effect all the rest. It will be proper to strut the joists from one to another by any scrap pieces of timber that may be found about the building, as it will be seen that the straps go cross-wise or through the spars, and contrary to the plan before laid down for the beams, an ordinary floor may now be fitted on, and our work is completed; with this one difference, that we have a power to sustain permanently and securely a much greater weight than the timber named above could sustain, nor is it subject to the same undulating motion when walked upon. proper firmness and rigidity being obtained, which can be procured only with great diffi. culty and expense, when the spars are made of wood entirely.

A

"Fig. 8 represents a compound floor constructed according to our improved method, but without joists for either floor or ceiling, and partaking of the nature and application of the laminated beam, but being used hori.

zontally instead of vertically. A is the floor, the boards being arranged some diagonally and some at right angles upon each other, and nailed together; B is one of a series of segmental hoops stretching underneath the floor and fastened to and through the wall plates CC; DD are stays, stretching from the floor to the hoops; thus it will be seen that with the addition of a little extra wood for the floor board, joists, &c. are useless. A floor 20 feet square would require four straps, as named in fig. 7, instead of three, and an additional half inch of timber, or three boards of half inch each would make a floor equally as sound for bearing weight as the one planned under No. 7, the ceiling would at once be made, avoiding the necessity of lath and plaister, and might be ornamented with reeding round the hoops and in place of the usual cornice. In some floors we would recommend an interior layer of brown paper between the ranges of the boards; the whole is then to be nailed together with strong sprigs and well turned."

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* * * * "Galleries.-A laminated beam of a sufficient depth to form the front of the gallery and resting upon the end walls would require neither beam nor pillars to support it. Upon the foot of this beam, spars might be placed, stretching from it to the back wall for the foundation of the gallery, and thus the other rows of the pews may be projected.

"This plan may be varied by doing away the spars above spoken of, and each row of the pews in the gallery may be supported by laminated beams, placed and affixed from wall to wall as in the instance of the front of the gallery; but underneath and as high as the seat in the back of each pew, aiding in part the erection and formation of the pew, and being not only a support for the seat in one pew, but giving a support for the floor of the pew behind it (see fig. 9). Much greater head-room will thus be given underneath the gallery, and a great saving effected."

both by calculation and experiment, the next thing that became desirable was the power of propelling and guiding them at will.

Various attempts have at different times been made to accomplish this eminently desirable object; but being for the most part made without judgment, they were unattended with successful results. Sufficient has been done, however, to prove beyond all question, that propellers will act upon a balloon, with an effect proportionate to their size, and to the manner in which they are placed and worked. It is also equally evident, that so soon as ae onauts can, by any means, cause their balloon to move with a velocity differing from that of the current of air in which they are floating, a rudder will become efficient, and the balloon will answer to the helm.

People frequently confuse themselves in their application of the simple price ciples of navigation in a denser medium to aerial navigation.

So long as a boat, barge, &c. moves with the same velocity as the stream, a rudder is wholly useless; but, if the boat or barge is made to move with a different velocity-i. e. either faster or slower than the stream-the rudder becomes an efficient agent in directing the movements of the vessel. With balloons, precisely the same law obtains; the moment they can be propelled, they will become capable of being guided.

In a recent Number of your Magazine, Mr. Mackintosh very justly observed, with respect to the difficulty of propulsion, that "the difficulty consists simply in this:-The resistance is greater than any power that has been hitherto applied 6. Το to overcome it." He further adds, meet this difficulty we must increase the power, and decrease the resistance.”

Mr. Mackintosh's reasoning upon this subject is perfectly correct; and I have now to state, that following out precisely the same principle, I have succeeded in contriving a balloon of an entirely new description, possessing all the requisites for efficient aerial navigation, and capa. ble of being propelled and guided at the pleasure of the aeronauts. The few scientific friends to whom I have 'sub, mitted my plans, have expressed themselves perfectly convinced of their feasi bility, and feel satisfied that the time has

now arrived when balloons will cease to be scientific toys, and assume a new and useful character.

It would not be consistent with my own personal interest, at this time, to develop the nature of my invention, but your readers will hereafter have an opportunity of becoming acquainted with it. I should wish no person to suppose for one moment that balloons will ever be guided in the teeth of opposing currents; but I am now prepared to assert, and all who have examined my scheme will support my position-that in balloons upon my construction, the power is so much increased and the resistance so much diminished, as to enable them to be propelled and guided through the air with as much facility as boats at present are upon the surface of our river Thames.

By the same means, an upward or downward direction can be given to a balloon, without in any way varying the quantity of gas or of ballast-and the machine brought under a degree of control hardly before anticipated.

I remain, Sir, yours respectfully,
WM. BADDELEY,

For the sake of brevity, I will skip over electricity, which is a mere artificial excitation and exhibition of the base of all things, to say a word on galvanism. The galvanic action is an excitation communicated to certain substances, through which they are provoked to an energy of expansion, that is, of separation, which produces phenomena more apparent to our senses than such action would be without such superposition or arrangement. If we place together two pieces of copper, for instance (the degree of action of the two being equal), the product only induces an equilibrium of mixture, that is to say, two pieces of a given substance are just as though there were only one. But if we place in juxta-position two bodies of analogous natures, but of different capabilities of internal expansion, the one of these bodies which is the most active in expansive force will give

out a major, the other a minor fluid. A plate of copper placed upon a plate of zinc, it follows that all the molecules of the major order (the North Pole) flow to one of the two, that is, to the most die lated and active, and, expelled by the internal expansion, they are accumulated on the surface of that plate, as they cannot be contained within it. On the other hand, all the molecules of the minor order, contained in the two plates, are thronged upon the more condensed plate, and remain in abeyance on its exterior. We here have the complete magnet-the face of the zinc is the major pole, that of the copper the minor. The space be tween them is the neutral ground, or region of indifference. The addition of water increases the expansion, separation, circulation, and escape of the molecules of the metals, by acting as a conductor and stimulant. If you wish to increase the exit of galvanic fluid, i. e. the ema nations of the substance of the metals, submit the pile to mechanical pressure and just as you would force water out of a sponge, so will you expel a greater quantity of organic fluid (the galvanic) out of the metals. The water and salt, or acid, not only serves as an excitant and a conductor to the expansive products of the couple of metals, but, by its decom position, furnishes molecules of a perfectly similar nature to those of the metals. If the pile be isolated, the centre of it is neutral, and in equilibrium of mixture; but if the lower extremity communicate with the earth, the intensity of action is very greatly increased; because the expansive fluid is received from an indefinite extent of surface, that is, from the earth itself. A double flow now takes place; from the earth to the column, and from the column to the earth. minor fluid now flows from the superior extremity of the column into the earth. The major fluid ascends from the earth into the column with great intensity, so that it is now at the superior extremity only that a great accumulation of electric fluid is established. In this state of things, the pile resembles the Leyden bottle, as at its upper extremity it will give out sparks; and if with the hands you touch, at one and the same time, the two extremities, a commotion will be felt. That the emanations, or expansive perspiration of the earth, is identical with

The