ship-like car, which was to have masts, sails, and rigging, and sailors, to manoeuvre it; and, above all, metal lightning-conductors from the top of the masts to the bottom of the car! Pray where did he mean the electrical fluid to go after it had travelled through the rods?

As to the objection, that gas-balloons are liable to burst, no accident has ever happened in that way; although there, are several instances on record of balloons being rent by the extension of the gas, yet they always came safely to the ground, the flaws being only large enough to allow of a gradual escape of the gas. After all, in my opinion, the two kinds of balloons are about upon a par as regards safety, and I would as soon trust myself with the one as the other.

As a Montgolfier is, however, evidently the cheapest, I would make a suggestion as to its greater security: might not that part of the balloon in the vicinity of the fire be made of asbestos? And, further, would not woollen or worsted stuff be less combustible than cotton? A spark or flame applied to the former would only singe the portion in immediate contact with it, while the latter would blaze up.

For security, in respect to both kinds of balloons, I would suggest that the car should be so balanced that, in the event of the sphere bursting or being burnt, it would maintain an upright position in the air, and fall with its bottom downwards. The fall would also be greatly broken by a parachute of very moderate dimensions, and on touching the earth, still further by helical springs in proper positions on the bottom of the car. An

aeronautic life-preserver might be made in the shape of a loose dress attached firmly round the shoulders, stiffened with ribs of whalebone, hinged at that part; each of which ribs should have a stay from near its extremity to the waist, so that in the event of an aeronaut falling out of the car, or the destruction of the balloon, the parachute dress would expand and bear the wearer gently to the earth. A parachute of about 12 feet diameter was found by Mr. Blanchard to be sufficient to bear a inan safely to the ground from any height; and M. le Normand threw himself from a house, and descended in safety with a parachute of only 30 inches diameter.

These precautions should not be considered as unnecessary, or out of place,

when aerostation has become so popular that ten or a dozen persons ascend with one balloon.

I will now, sir, make a proposal, which I leave to your discretion whether to make public or not in your Magazine., Taking advantage of Colonel Maceroni's offer of assistance, I would propose an "Aeronautic Club," consisting of about a dozen or more gentlemen, who, by subscribing a few pounds each, might have a Montgolfier balloon constructed, in which the subscribers should ascend by turns, to he decided by lot-some for scientific observation, and others for mere curiosity.

I have made a rough calculation of the probable expense of a balloon for such a club, and I here submit it to your readers." The Colonel says, a Montgolfier, 40 feet diameter, would take up four persons. Suppose, then, we estimate for one of 50 feet diameter to carry five persons; the rule to find the quantity of cloth required, as given in the Edinburgh Encyclopedia, is to multiply the square of the diameter by 31416; therefore, 50 x 50 = 2500 X 314167854 feet 2618 yards, which at 6d. per square yard (a good price for cotton, or bombazet as before suggested), would be 651. 9s.; and for making say, 107. Of the other expenses, the Colonel' is no doubt better able than I am to give an estimate; with which he will perhaps oblige your readers, as also with an opinion of the plan. With your permission, sir, your publisher will take charge of any letter from parties desirous of joining the club, addressed to, Sir, your obedient servant,

UMBRA MONTGOLFIERI.

THE DAVY-LAMP.

Sir, It is evident from the commencement and termination of your correspondent "Black Diamond's" letter, which appeared in your publication of the 10th inst., that he labours under the impression that the Davy-lamp has not yet been proved insecure, by "the inflammable gas actually evolved in coal-mines." The contrary is the fact; the error general. A reference to the evidence given before the late Committee on Accidents in Mines, will show that the trial of that lamp has not been confined to factitious gases. Mr. Buddle's evidence, p. 154,, records its first trial and failure.

He

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says, "I held the lamp in the direction of the jet of fire-damp, and not having seen it explode before, I was not very apprehensive of its firing. It did not fire at first; but as I approached the end of the pipe, the gauze became heated" red-hot, and passed the explosion. The flame was as long or longer than the breadth of the engine-room. I remember it burnt the nap off my great coat and spoiled it. The experiment was repeated over and over again." It may be observed, that this experiment was tried as long since as the year 1816. The inflammable gas issued from a blower in the Morton West Pit, one of the Earl of Durham's collieries. Sir H. Davy was present, and it appears, from Mr. Buddle's. account, explained on the spot the danger of exposing the lamp to a current of explosive mixture (fire-damp), as he said it would risk the passage of the flame through the gauze.

Another recorded and recent instance of its failure with fire-damp, attended with a fatal result, is described by Mr. George Mitcheson, an extensive mineagent, and one of the witnesses examined before the Committee, who states, p. 190, "that he saw two men go down the Green Dock Pit, Staffordshire, with a Davylamp; and that after they had descended, a pail of water was thrown down the shaft, with an idea of increasing the ventilation. That as soon as the water was thrown, the pit fired, and one of the men was killed; the survivor, who was sadly burnt, said that as soon as the wind came, the gas exploded—no other light was in the mine at the time." The next witness, Mr. William Forrester, agent to the Earl of Granville, states, p. 199, "I have seen a lamp (a Davy) fire the carburetted hydrogen gas in a thirling." I shall conclude this part of the subject by a reference to a trial of the Davylamp, also with the actual inflammable air evolved from coal, described in a certificate presented by Mr. Roberts to the Committee on his examination, and published by them, p. 260. It states-"On the inflammable air being brought to act on the Davy-lamp, the flame passed through the wire-gauze and ignited the gas outside." This experiment took place in Parks's colliery, near Dudley, March, 1834. The inflammable was taken from a sumpt in the colliery, and its explosion witnessed by M. Parks and seventeen

other persons, his workmen, who signed, the certificate referred to.

It may be urged, though I do not expect it will by so intelligent a person as your correspondent, "Black Diamond," that the Davy-lamp ought to be considered safe because it has never been proved unsafe in a quiescent atmosphere.. If this argument be used, I shall not be so wasteful of your valuable space, even if you would permit it, as to attempt its refutation; for surely the claim of “safety” ought not to be allowed to an instrument, the protection of which can be destroyed by that which is ever to be expected, is of frequent occurrence, and against which no human care can guard-viz. the agitation of the atmosphere of a coal-mine. If this, sir, were a subject on which individual feeling could with propriety be expressed, I should thank your correspondent, B. D., and yourself, at some. length, for the opportunity this letter gives me of making the fact known, that the Davy-lamp has been found insecure -not only with factitious gases, but with the inflammable air of coal-mines. I remain, Sir,

Your obedient and obliged servant,
GEORGE UPTON.

London, Sept. 21, 1836.

BEST WIDTH OF RAILROAD TRACKS. (From the American Railroad Journal.) Sir, In a late Number of the Railroad Journal, I observe a communication from the President of the New Orleans and Nashville Railroad Company, in which it is stated that engineer H. J. Ranney, Esq., of that road, proposes an increase in the width of the railway track, viz. 5 feet instead of 4 feet 8 inches, the width generally adopted, and requesting the opinion of professional men on the propriety of the change. It has long appeared to me that our engineers were labouring under a mistake, in restricting the width of track upon our railroads to 44 feet. My reasons for this belief, I will briefly state as follows:

1st. By increasing the width of track, the maximum speed for safe travelling may be increased. This is owing to the fact, that with wheels of a given size, the breadth of base compared with the height or elevation of the centre of gravity of the load is increased the carriage, when under an equal motion, possesses therefore greater stability, and will bear a greater speed without increasing the danger of "flying the track."

2nd. The diameter of the wheels may be

am entitled to do, to state in your journal, without reserve, where and in what manner my process of condensation has been practised forty years agol I must observe, too, that this assertion is no answer to the questions I put tochim tending to place the point Patrissues inva tangible position, and I must, therefore, again call his attention to the them 990

Your most obedient servant,

THOMAS HOWARD.

7, Tokenheuse-yard, Sept. 20, 1836.

Hargsbry.

RAILWAY COMMUNICATION.E (From the Athenæum Report of the Meeting of the 20763 01 British Association.)ismiw den At the late meeting of the British Association, at Bristol, Dr. Lardner stated some statistical results arising from the establishment of railway communications. The subject to which he would call the attention of the Meeting, was one which, at the present time, was particularly interesting but it was not for the purpose of showing how far railway speculations, as such,might become profitable, that he should bring them forward he had a higher objeet, which

was

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s that of endeavouring to ascertain, and if possible, to establish the general law aw which governed the increase of intercommunication which they led to. He was not prepared to lay before them any particular results, as to the general effects of railways; he should confine himself to a few facts which seemed to shadow forth the probability of a statistical law in reference to the point to which he had alluded. When the Liverpool and Manchester railroad was projected, it was designed for the transit of goods only, at the rate of ten miles per hour; but it was unexpectedly found that treble speed was attainable, and then passengers became the primary consideration. Previous to the establishment of the railway, there were 26 coaches between Liverpool and Manchester, and the number of passengers making one trip was about 400 per day. Immediately on the establishment of the railway, that number rose to 12,00; thus, in the very outset, an increase took place in the proportion of 3 to 1. The railway had been in operation, he believed, since 1828, and from that period the number of passen.. gers had gone on increasing, with the exception of the period of the cholera, which might very fairly be omitted in

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his calculations, and now the number was 1500 per day, being a further increase of one in four; and thus it appears that no less than half a million travel by it annually. Now, the population of Liverpool was 165,000, and that of Manchester 183,000, making a total of 348,000; and thus they would see that, out of those Hopulations, an intercourse of more than half a million took place annually. The time by the fastest coaches was three hours: the time on the first opening of the railway was, by the fastest trains, one hour and a half, now it wes but an hour and twenty minutes. The fare of the coaches was, outside, half-a-guineawhat it was inside he could not then recollect by the railway, the average fare was 4s. 6d. In this instance diminution of time and expense both combined to increase the number of passengers; and the increase, it should be borne in mind, was exactly fourfold. The second example he should refer to, was the railway between Newcastle and Hexham; before the establishment of which, the number of passengers by coach monthly was 1700; it is now by railway 7060, being rather more than a four-fold increase. Now, the village of Hexham was by no means an important place; on the contrary, it was so insignificant that

the wonder was, what c could possibly require 7060 persons to go upon the railway. His third instance would be the Dublin and Kingstown railway. The city of Dublin contained 200,000 inhabitants, and Kingstown, which was distant about six miles, contained 6000 or 7000. There was no manufactures, no trade there: true, there was a harbour, but it was used exclusively by the Post-office packets; none of the commercial vessels-not even those who might be driven in by stress of weather-being permitted to discharge their cargoes consequently no goods were carried on this railway. Now, when he stated what was the intercourse actually existing, under these circumstances, it must be admitted that the effect exercised upon it by the packets was very insignificant. The intercourse previously existing, too, it must be borne in mind, was carried on by means of a rude vehicle called an Irish car, and in this manner they were carried at prices varying from 5d. to 7d., the proximate number being about 800 daily. The railway had been opened about two years,

and the intercourse was in the ratio of a million of persons annually. Now that furnished another example of the numerical proportion previously referred to: for if they took the number of passengers before the opening of the railway at 800 daily, it would be found that the proportion of four to one would give 3200, and 3300 was the average of the present number-the travelling on the Sunday being 7000, the proportion the other days less; but the average above given being fully made up. He had thus shown that the law of increase was fourfold; he would now show that it depended infinitely more on the saving of time than money. On the Liverpool and Manchester railway the price was less than one-half the charge by the coaches; but on the Dublin and Kingstown railway the charge of conveyance was absolutely raised, and, besides that, the railway did not reach the latter place by half a inile, which occasioned to many an additional charge for carriage-hire to take them over the remaining ground. On that railway there were three classes of trains, and the fares were 1s., 8d., and 6d. ; the carriages most filled being those at 8d.; it was quite fair, therefore, to assume that, in this instance, three out of every four travelling on the railway did so merely on the score of the saving of time. It would be well if they could go back and see what were the effects produced on intercourse by the establishment of turnpike roads and the introduction of coaches; they would find probably that the great increase had been wholly owing to the time saved by the improvements effected. It was remarkable, however, how much results varied, for he had ascertained that, though much improvement had of late years been effected in the mode of travelling by canals-in certain cases the boats having attained to a speed of 10 miles per hour, equal to that of the caches, while they carried their passengers at a far cheaper rateyet he did not find that they added much to the intercourse. He alluded more particularly to the boats on the Kendal and Preston, and the Edinburgh and Glasgow canals; and, he asked, could it be doubted, if railways were running parallel with them, that an increased traffic would immediately take place? He mentioned this merely to show how much more economy of time was re

garded than the mere saving of money. Dr. Lardner then proceeded to remark on the value to new companies of the experience gained in working the Liverpool and Manchester railway. The charge for transport of passengers on the Manchester railway was 1.84-100ths of a 1d. per mile, the actual cost to the proprietors about 1d. per mile: whereas a Birmingham manufacturer had entered into a contract, by which the whole of the passengers on that line woald be conveyed at the cast of one farthing a mile, including every expense of locomotive power, the company merely finding the carriages and the road. The same company had also formed a contract for the conveying of goods at 1d. per ton per mile, the contractor, as in the former case, defraying every charge for engines, &c. Dr. Lard ner then proceeded to show the possibility of attaining so high a rate of speed as 50 miles per hour, and dwelt at great length on the effects likely to result to the general commerce of the country.

WIRE-PLATE ENGRAVING.

Sir, I herewith send you a description of a proposed new mode of engrav ing, of my invention, to be called wireplate engraving; and it will give me great satisfaction if you think it worthy of insertion in your Magazine.

The wife-plate engraving is intended as a substitute for wood-engraving, on account of its possessing some advantages over it, as may appear from the following description, which, in order to make clear, I propose to consider the matter under two general heads; first, a description of the wire-plate itself, and secondly, the mode of engraving upon it.

1. The wire-plate is composed of a number of very fine wires laid parallel together, and closely packed in a metal fraine. In this state the wires, together with the frame, constitute a plate, whose two opposite surfaces are composed of the ends of the wires, as these are presented outwards or on each side, of the plate. The wires may be about a quar er of an inch in length, or from that to half an inch, according to circumstances, and are to be of the finest steel or brass wire that can be procured; so fine, indeed, as that their diameters must not exceed 150, or even 200, to the linear inch; though if their diameter exceeded that