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are resident in Liverpool, the Directors are happy to state that they have at the same time added to their body, two gentlemen whose assiduous habits of business and intimate acquaintance with railway matters, are like to render their accession to the direction of the greatest advantage to the interests of the Company.

It may be proper to add, that by the Act of Parliament a certain fee is authorised to be taken ou each certificate of registry and each transfer of shares; but that the Directors, considering that the levying of such a fee would impose an unnecessary tax on the shareholders-in the first stages, particularly, of the undertaking - have ordered that it shall not be enforced.

Signed, on behalf of the Directors,

HENRY BOSANQUET, Chairman, R. J. HARVEY, Deputy Chairman. -18, Austin Friars, Sept. 26, 1836.

CORNISH STEAM-ENGINE WORK.

Sir, The object of my former letter has been attained by Mr. Dickson's expression that I have taken upon myself to be the champion of the Cornish engineers; and also by his corrected restatement of my assertions. With regard to comparative calculations of steamengine work, it appears to me, that since either, 1st, the weight moved-2d, the height or distance-or, 3d, the quantity of - coal used—may be made the varying quantity (railway locomotives adopting the last, and pumping-engines the first method), the suggested change is without a definite object. The argument rela`tive to rain-water is good; and the strict est examination into Mr. John Taylor's data is desirable, to ascertain whether he Irassufficiently allowed in his calculations, not only for this point, but for the different circumstances attendant on the working of the mines adjoining Dolcuath and C Consols. This argument would have had more force if the probable effect of the sextension of levels had been accounted for, and not omitted. The observation relative to the depth from which water is drawn in some mines seems to me to be a sufficient answer to the sentence which follows, and confirms, moreover, my assertion of the difficulty of ascertaining the exact delivery of water from eight or mine lifts, many cisterns receiving part of their water from the lift below and part from the adjoining levels.

Since the public are said to take an interest in this subject, I will address a few words to such of them as are em

ployers of steam-engines, as I fear an expression in my previous letter might tend to countenance an erroneous opinion of the control of the engineers over the report of "work performed by steamengines in Cornwall," should its existence be known to them. The duty, as calculated from the number of strokes registered by the counter first used by Watt as a check on the mining adventurers or proprietors, has been since 1812 used by the latter as a check on their engineers; and I conceive the real question to be, not whether such check is quite exact, or not, but whether it is a proportional test of a steam-engine and its pumps; whe ther it is as fair in the present as in the last century. As such it was adopted by the mining adventurers; and its variation in every monthly statement, from twenty to ninety millions in different eugines, is rather an argument of " Fair Play, and no Favour.' With regard to ascertaining the difference between the actual and calculated delivery of water, it is necessary to lengthen the pump or rising main the height of the required cistern; and this must also be done at each cistern which receives water from the levels adjoining. Perhaps one of the larger mines might undertake the neces sary trouble and expense for the satisfac tion of known parties of eminence; but certainly not to satisfy idle curiosity, and most assuredly not to answer a protest, whose tone has a tendency to defeat its professed object.

Whenever a protest appears supported by calculations pointing out the mode in which the asserted errors have found their way into the stated amount of the present duty of good engines-particularly if the mines have been examined by its author I feel no doubt it will meet with due attention. The private premiums awarded through the medium of the Polytechnic Society in the present and preceding year, are perhaps the strongest protests yet made relative to this point. As an individual, I have constantly proposed to deduct from Watt's duty a quantity pro portional to the difference, when proved, between the actual and calculated delivery of water-first making the allowance of the difference of the Imperial bushel of 94lbs. of Welsh coal as compared with the Winchester of 89lbs., Newcastle or engineer's coal being about 88 to 81lbs. The only published account, I believe, of any monthly duty of Watt's engines

during the patent is in the Philosophical Transactions for 1830, which contains also the document on which Watt's agree ment relative to the savings of coal was founded. I have always observed that the objectors to that agreement forget that the delivery of the water by the trial deficient. pumps was proportionally

Should any person be unwilling to agree to this compromise, I then clann a superiority of the present delivery of water greater than the difference of the bushel of coal, and call for proof of a greater monthly duty than twenty-nine millions during Watt's patent.-Yours, &c. JOHN S. ENYS.

Enys, Sept. 25, 1836.

MR. MACKINTOSH'S SECOND LECTURE ON HIS THEORY OF THE UNIVERSE.

"

This lecture (delivered on the 10th inst.) related to the laws and sources of motion. Mr. Mackintosh commenced his observations by referring to Newton's first law of motion, that if a body be at rest, it will continue at rest; and if in motion, it will continue to move uniformly forward in a right line, if it be not disturbed by the action of some external cause. Upon this law the whole Newtonian system was founded, and the law, he remarked, would be true, provided all the condilions were fulfilled. To satisfy those conditions, he observed, we must suppose space to be void of all matter, except the said moving body,which supposition would be opposed to our knowledge, that space is filled with innumerable bodies which, by their mutual attractions, act and re-act on each other. No body, he said, could pass through the solar on any other similar system without being subject to the disturbing action of external causes, therefore the whole Newtonian system was founded upon an imaginary axiom which had no existence in nature. He next proceeded to observe, that the Newtonian system recognised only one proper force, gravity, under the action of which all bodies tend to a centre; he contended that momentum, or a centrifugal force (as it was called), was no force, but merely an effect de rived from a force; and might be destroyed by force; that therefore the Newtonian system recognised only one real force, gravity; that the momentum, supposed to be derived from an original impulse, was continually di minished by the force of gravity, and therefore, if the motions and distances of the planets were determined by gravity and momentum alone, they must all have merged in the sun thousands of years ago. The g eat fallacy of the Newtonian system consisted, he remarked, in considering momen tum as a real force.

He next proceeded to show, that all motion whatever might be traced to the expan sion and contraction of matter under the directing will of the Deity, and laid down

the following axioms to illustrate and support that proposition.

1st. The expansion of matter results from its decomposition by chemical action; and may, therefore, be called chemical motion, or the repulsion of particles.

2d. The contraction of matter, resulting from the action of gravity, may be called me. chanical motion, or the attraction of particles.

3d. All chemical motion resulting from the decomposition of matter tends from a centre to a circumference; at any distance from that centre, the distance to which the motion pro. ceeds from the centre, being greater or less, as the intensity of action or quantity of matter is greater or less.

4th. All mechanical motion resulting from gravity tends from a circumference to a centre, the time which the motion continues being greater or less as the velocity or distance from the centre is greater or less.

5th. If chemical motion continually tends from the centre to the circumference, a perpetual chemical motion is impossible, be cause whatever may be the dimensions of the mass, it must have a centre, at which point chemical action would cease.

6. If mechanical motion continually tends to a centre, a perpetual mechanical motion is impossible, because whatever may be the dimensions of a circle, it must have a centre, at which point mechanical motion would

cease.

1

7th. But a perpetual motion may, and doea exist, and is a necessary result of he two forces, viz. of chemical motion tending from a centre, and of mechanical motion tending to a centre, and these two forces may, and will continue to produce motion for ever.

He next proceeded to show that all motion was produced by these two forces; that the sources of rivers were supplied by rainswhich receded from the earth in an expanded form, and returned again to the earth in a condensed or contracted form; that the motion of the atmosphere was produced by the same forces; the motion of the steam-engine, and even animal motion, which is dependant upon the pulsations of the heart, he traced to the expansion and contraction of matter, applying the same principles, in an extended sense, to the whole universe.

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VOL. XXVI.

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WITTY'S PATENT LAMELLAR BEAMS AND

SEGMENTAL TRUSSES.

Mr. Richard Witty, already known to the engineering and mechanical world for numerous useful inventions, has recently patented what appears to us to be a very important application of two acknowledged principles in mechanics. The first is, "that the transverse strength of a beam, joist, or spar, bears a certain definite proportion to its depth, breadth, and length; also that double the depth of any beam, joist, or spar, of the same breadth and length, will bear four times the weight" the second is, that "all materials, whether wood, iron, or any other metal, resist by cohesive power a greater force than they can bear by a transverse strain." Mr. Witty's application of the latter of these principles in the segmental hoop truss is the most valuable part of his patent, and a decided improvement in the art of building. We shall lay before our readers a description of the invention, together with an exposition of its application to various purposes, from a very clearly-written pamphlet on the subject. We have no doubt but that as soon as the invention becomes generally known, it will be very extensively adopted, in the construction of roofs, floors, and galleries. We have our doubts as to its utility for railwaybars; quoting, however, what Mr. Booth says upon this point of the subject, we shall leave parties interested to form their wn opinions upon the matter.

First, with respect to the lamellar beam. After stating the principle first above quoted, Mr. Booth proceeds:

"If any beam whatever was sawn into two parts lengthwise, and each piece placed and fastened upon the other edgewise, the same quantity of material would bear double the weight to what it bore before the division took place. If this plan be followed up by dividing these divisions again in the same manner as before, it will be evident that it would bear this second time twice the weight it bore by the first division; or, quadruple

A Popular Treatise on the Strength and Application of Materials used in Buildings in general; showing the Advantages to be derived from the Principles of the Patent of Messrs. R. Witty and Co. in all Architectural and Engineering Constructions, comprising Bridges, Viaducts. Houses, Warehouses, Railroads, &c. By G. R. Booth. pp. 35. London, J. Weale; Newcastle, W. H. Hyde.

the weight it bore in its original state. Now, if the beam we speak of had been only ONE INCH wide in the first instance, it would have "been one quarter of an inch in width after these divisions were made. It will be obvious, that no use has been made of timber so thin as one quarter of an inch broad for carrying weights in buildings, and our object is to lay before the public a plan to avail themselves of these advantages required. It is obtained by making this practical deduction, that a number of thin plates, or laminæ of wood or iron, when placed together edgewise will bear considerably more than the same quantity of wood or iron in a square and undivided form. The difficulty of putting this into practice has hitherto been owing to the great tendency of thin plates to bend or deflect sidewise, or laterally, when pressed upon by heavy weights at the top, and to the great difficulty of so binding together any number of thin plates in such a manner as to prevent that deflection from taking place. Now, by this method, the tendency of thin plates to deflect laterally is totally counteracted, and the superior strength of lamellar combinations is rendered universally available for buildings and other constructive purposes: plates or laminæ combined, may consist entirely of wood, or entirely of iron, or of wood and iron jointly. Let us take sheets of rolled iron and place them edgewise (being governed as to their number and breadth, &c. by the degree of strength required in any particular case), and let us insert between every two of the iron plates, one plate of oak, fir, &c. (charred, or painted, or plain): this being done, let us pin or bolt them together, so as to form them into one compound beam. The two outer plates should be thicker than any other, in order that they may better sustain the pressure of the pins, and resist the lateral deflection. The length, too, of these plates need not be extreme, although a long beam be required in some buildings, where great lengths of timber are eagerly sought after, and a much larger price is given than for ordinary lengths. The necessity for such extreme lengths is obviated by the facility that this plan affords. Different lengths may be so arranged, that no two ends of these plates shall coincide with those of the next row of plates, the fastening-pins may be placed at the different points of junction, which will give us the advantage of obtaining beams of any required length or depth. By reference to the accompanying drawings (see front page), fig. I represents a plan of a beam formed in the manner here described, where the laminæ or plates are all of the same length; and fig. 11 a plan of a beam in which all the plates are of different lengths, and which may be continued so as to form a

beam to cross a warehouse, or any other erection, of any desired width."

In the formation of this lamellar beam we think an important point in the nature of the strain upon a beam has been overlooked. A beam supported at each end, on its being bent by any superineumbent weight, the particles or fibres in the upper part are crushed, and those in the lower part are stretched, while there is a point where the particles or fibres are at rest. Now, it is evident, that either Mr. Witty's or a common beam would be much strengthened by a plate of iron, or some other means being used to support the upper particles or fibres of the beam from the crushing, and the lower from the stretching tendency of the weight. As it is, however, the adoption of the patent beam resolves itself into a question of weight, material, and expense.

With respect to the beam, fig. 1", which is proposed to be made of any length by the alternation of the joints of each lamiua, we fear that there is too much dependance placed upon the fasteningpins.

Secondly, the segmental hoop truss:—

If a beam were to be torn asunder by a power pulling at each end, those powers would require to be much greater than the power or weight required to break it, when placed in a transverse position, and supported at both ends; this cannot be better elucidated than by the familiar experiment made with a small walking-stick. In taking hold of it at both ends we can easily bend and break it transversely; but if the force be applied in the direction of its length, two persons cannot tear it asunder with their united strength; the power or force exerting its influence under the last named trial is called the cohesive force. It is by the application of this power we purpose to aid beams, &c. to bear a greater transverse strain, or, in other words, to enable a beam to support a much greater weight than it could otherwise-this we apply where great weights are to be borne, as a subsidiary effect to the lamellar beam at the same time, the plan will be obviously useful elsewhere. The applications may be numerous: examples offering in all buildings, both for joists, rafters floors, &c. wherever architectural and engineering constructions are required to sustain weights;-considerably less materials than by any of the known methods of girding or trussing will suffice. The mode of effecting this, is to place under the beam, regularly formed curves or seg

ments of circles, or segmental hoops, secured at the ends of the beams; as will be shortly shown. The beam will form a chord line to the segment of a circle; between which and this segmental hoop, there must be placed blocks at various distances neatly fitted to the hoop, and attached only to the beam, but not to the hoop-there it must be at liberty, and to be perfectly effective should never be less in depth, than one inch in every three feet of the length of the beam. The end also of the hoop should pass through the centre of the ends of the beam, preserving the proper curvature, and having there an additional thickness of iron to screw to. Fig. 2 represents a hoop of this description, A is the beam, B the iron segment applied to the under part of the said beam and secured to the ends by the nuts and screws CC, which may be also forelocked for more security. DDDDD are blocks or stays of wood or iron, inserted at regular intervals, as noticed above. Now, by turning the nuts CC the blocks DDDDD are pressed upwards against the beam A; because the segmental hoop, when screwed up, endeavours to form itself into a straight line; the whole is thus so intimately and firmly bound together, that any weight placed upon the beam is equally distributed over the entire mass; and the beam will sustain uniformly throughout its length any properly apportioned weight. The arc of a regular circle (fig. 3,) will be

B

3.

D

found to have superior and manifold advantages to the curve of any other form. This will be best made of strong hoop iron, or bar iron, carefully bent into a curvilinear form. One moment's reflection will develop the utility of this application; we all have no ticed how small the hoops are required for a cask containing the greatest weight. Our diagram, fig. 2, is so drawn as to show that the segmental hoop we employ is simply a part of the whole hoop of a cask arranged by the peculiar attachment we have given it in the nuts and blocks. We have made this part to partake of the full power and effect of the whole hoop, as if it remained one entire part of the hoop; whereas we have detached

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