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there will be a tunnel, called from a martello tower near it, the Tower Tunnel, one third of.a mile in length. Then comes a cutting through the chalk of two miles in length, called Warren's Cutting. Then comes the Abbott's Cliff tunnel, one mile and a quarter in length, and now half finished, although only commenced on the 16th of August last. From the Abbott's Cliff tunnel, to the Shakspeare Cliff tunnel the railroad will be under the cliffs close to the sea, and protected from it by a strong wall of concrete two miles long, and with a parapet of such a height as will not preclude passengers from the splendid marine view which lies under thein. "Now it was found that when a straight line was drawn from the eastern mouth of the Abbott's Cliff tunnel to the western mouth of the Shakspeare tunnel, there was a projection on the Round Down Cliff which must be removed in some way or other to insure a direct passage. That projection, seen from the sea, had the appearance of a convex arc of a circle of considerable diameter. It is now removed, and some idea of its size may be formed from the fact that a square yard of chalk weighs two tons, and that it was intended by this day's experiment to remove 1,000,000 tons. The Shakspeare tunnel is three-quarters of a mnile long, and it is about the same distance from that tunnel to the town of Dover.
Having premised thus much as to the locality of Round Down Cliff, I now proceed to describe, as briefly as I can, the means employed to detach from it such an immense mass of solid matter. A horizontal gallery T, Fig. 3, extended for about 100 yards parallel with the intended line of railway, from which cross galleries were driven from the centre and extremes. At the end of these cross galleries shafts were sunk, and at the bottom of each shaft was formed a chamber, 11 feet long, 5 feet high, and 4 feet 6 inches wide. In the eastern chamber were deposited 5000lbs. of gunpowder, in the western chamber 6000lbs. and in the centre chamber 7000lbs. making in the whole 18,000 lbs. The gunpowder was in bags, placed in boxes. Loose powder was sprinkled over the bags, of which the mouths were opened, and the bursting charges were in the centre of the main charges. The distance of the charges from the face of the cliff was 70 feet at the centre and about 55 at each end. It was calculated that the powder, before it could find a vent, must move 100,000 yards of chalk, or 200,000 tons. It was also confidently expected that it would move 1,000,000 tons.
The following preparations were made to ignite this enormous quantity of powder :-At the back of the cliff a wooden shed was constructed, in which three electric batteries were erected. Each battery consisted of 18 Daniels' cylinders, and two common batteries of 20 plates each, to which were attached wires which communicated at the end of the charge by means of a very fine wire of platina, which the electric fluid as it passed over it, made red-hot, to fire the powder. The wires covered with yarn were spread upon the grass to the top of the cliff, and then falling over it were carried to the eastern, the centre, and the western chamber. Lieutenant Hutchinson, of the Royal Engineers, had the command of the three batteries, and it was arranged that when he fired the centre, Mr. Hodges and Mr. Wright should simultaneously fire the eastern and the western batteries, to insure which they had practised at them for several previous days. The wires were each 1000 feet in length, and it was ascertained by experiment that the electric fluid will fire powder at a distance of 2,300 feet of wire. After the chambers were filled with powder, the galleries and passages were all tamped up with dry sand, as is usually the case in all blasting operations.
At 9 o'clock in the morning a red flag was hoisted directly over the spot selected for the explosion. The wires were then tested by the galvanometer, the batteries were charged, and every arrangement was completed for firing them.
It was arranged that the explosion should take place at 2 o'clock; at that time there was an immense concourse of people assembled. In a marquee erected near the scene of operation, for the accommodation of the directors and
distinguished visitants, we observed among the number assembled, Sir Jolin Herschell, General Pasley, Col. Rice Jones, Mr. Rice, M.P., Professors Sedgwick and Airy, the Rev. Dr. Cope, and there was also a strong muster of engineers, among whom were Mr. Tierney Clark, Mr. John Braithwaite, Mr. Charles May, Mr. Lewis Cubitt, and Mr. Frederick Braithwaite; the engineers and directors of the Greenwich, Croydon, Brighton, and South Erstern Railways, besides numerous foreigners of eminence.
At 10 minutes past 2, Mr. Cubitt, the company's engineer-in-chief, ordered the signal flag at the western marquee to be hoisted, and that was followed by the hoisting of all the signal flags. A quarter of an hour soon passed in deep anxiety. A number of maroons, in what appeared to be a keg, were rolled over the cliff, and on their explosion with a loud report, all the flags were hauled down. Four more minutes passed away, and all the flags except that on the point to be blasted were again hoisted. The next minute was one of silent, and breathless, and impatient expectation. Not a word was uttered, except by one lady, who when too late, wished to be at a greater distance. Galeatum sero duelli pænitet. Exactly at 26 minutes past 2 o'clock a slight twitch or shock of the ground was felt, and then a low, faint, indistinct, indescribable moaning subterranean rumble was heard, and immediately afterwards the bottom of the cliff began to belly out, and then almost simultaneously about 500 feet in breadth, with reference to the railway's length of the summit began gradually to sink.
There was no roaring explosion, no bursting out of fire, no violent and crashing splitting of roeks, and what was considered extraordinary, no smoke whatever; for a proceeding of mighty and irrepressible forze, it had little or nothing of the appearance of force. The rock seemed as if it had exchanged its solid for a fluid nature, for it glided like a stream into the sea, which was at a distance of about 100 yards-perhaps more-from its base, tearing up the beach in its course, and forcing up and driving the muddy substratum together with some debris of a former fall, violently into the sea, and when the mass had finally reached its resting place a dark brown colour was seen on different parts of it, which had not been carried off the land. The shattered fragments of the cliff are said to occupy an area of 15 acres, but we should judge it to be much less. I forgot to minute the time occupied by the descent, but I calculate that it was about four or five minutes. The first exclamations which burst from every lip was- "Splendid, beautiful !" the next were isolated cheers, followed up by three times three general cheers from the spectators, and then by one cheer more. These were caught up by the groups on the surrounding downs, and, as I am informed, by the passengers in the steam-boats. All were excited-all were delighted at the success of the experiment, and congratulation upon congratulation flowed in upon Mr. Cubitt for the magnificent manner in which he had carried his project into execution.
As a proof of the easy, graceful, and swimming style with which Round Down Cliff, under the gentle force and irresistable influence of Plutus and Pluto combined, curtseyed down to meet the reluctant embraces of astonished Nep. tune, I need only mention that the flagstaff, which was standing on the summit of the cliff before the explosion took place, descended uninjured with the fallen debris.
No fossil remains of the slightest importance were brought to light, which was a matter of disappointment to many. A very few even of the most ordinary character were found among the mass, which it may well be imagined was soon after the explosion, teeming with the curious multitude from the cliffs above anxious to obtain some relic of the event.
On examining the position occupied by the debris of the overthrown cliff, we were much pleased to find it more favourably disposed than we could have conceived possible. Instead of occupying the site of the proposed railway at the foot of the cliff, it bad by its acquired velocity slid past it, and left compa. ratively little indeed to be removed. At some considerable distance from the cliff, the fragments appeared to be heaved up into a ridge, higher than any other part, forming a small valley towards the cliff, and another seaward, beyond which a second ridge appeared, when it finally slopes off towards the sea. The chalk was by no means hard, and appeared thoroughly saturated with water. The great bulk of the fragments ranged from about 2 to perhap 8 or 10 cubic feet, although we observed a vast number of blocks, which contained from 2 to 3 cubic yards and upwards, one of which was driven some distance into the Shakspeare Tunnel, without doing injury to the brickwork. There was very little, indeed, of what might be termed rubbish in the mass.
Previous to the explosion, we had heard it stated that about a million yards were expected to be detached ; indeed the Railway Times so stated it, on the 21st ultimo, apparently from authority, and after the explosion took place, it was publicly asserted by one of the officials, that three quarters of a million of cubic yards had come down. Now, on cubing the stated dimensions of the mass, which were given as under 300 feet in height by, say 50 feet longer than the gallery, which would therefore be 350 feet, by an average thickness or depth from the face of the cliff of 60, we shall have 233,333 cubic yards; but as the present face slope of the cliff is greater than before, the average thickness perhaps might be increased to 75 feet, which would make the quantity 291,666 cubic vards. From this is to be deducted 50,000 yards, the estimated quantity to be now shifted in forming the road, we shall then bave 230,000 yards effectively removed by the expenditure of one ton of powder. We understand that Mr. Cubitt, the engineer, afterwards stated that a saving of six month's work, and £7000 expenditure was effected by this blast. Now allowing 6d. per yard for the removal of the quantity now required to be shifted, which would amount to £1250, and £500 for the powder used in the blast, the cost of forming the galleries, tamping, &c., &c., we shall find that this mass has been removed at a cost of 1.44 pence per yard. Again, taking Mr. Cubitt's statement, that a saving has been effected of £7000, to which, if we add the £1750, expenditure by the present plan, we shall find that he estimated the cost of removal by hand labour, at rather less than 7 d. per yard.
We felt an interest in examining the beds and fissures of the chalk in the neighbourhood of this blast, which clearly indicated that the plan of removal adopted by Mr. Cubitt, was not only the cheapest, but the safest method which could have been adopted. The vertical fissures which here traverse the chalk appear to lie pretty nearly parallel, and at a slope perhaps of one-fifth to one. tenth to one. It was in one of these fissures that the whole mass parted and slipped down, on which we believe it had set previously, no doubt brought about by the infiltration of water more than the sapping of the base by the sea. So treacherous indeed was this chalk, that if we are rightly informed, a mass equal nearly in bulk to that blasted on Thursday came down unexpectedly some time since in the night time, burying in its ruins a watchman or foreman belonging to that part of the line. In the zigzag gangways cut along the face of the cliff, to enable persons to ascend to the summit-this sliding of the chalk where those vertical fissures are intersected, appears very frequently, inspiring the passer-by with a feeling of great insecurity. How far the water might be intercepted, or otherwise be prevented from filtering through these fissures is a question of great importance, and would not, we think, he one of difficult remedy. It also becomes a matter of interesting inquiry as to the effect which a lesser quantity of powder would have had, deposited and fired in the same manner. Would it only have made the mass insecure, or caused a partial sliding down, rendering it then more difficult of removal by hand than at first? The proportion of powder which Mr. Cubitt employs in his blasting operations we understand is determined thus: “The cube of the line of least resistance in feet, gives the quantity in half ounces;" but in this case there does not appear to have been any such quantity employed, though much more than heretofore is found necessary in usual blasting operations. Perhaps the most curious circumstance, connected with the operation, was the apparent absence of shock on the firing of the charge on some spots in the immediate vicinity, while at others, far more distant, it was clearly perceptible. Thus where the batteries were placed, those in charge of them thought the charge had missed fire, from their being insensible to any shock, while at five times the distance along the face of the cliff, it was clearly felt. But even along the face of the cliff it was very evident ibat the shock was felt by some and not by others, though standing within a few yards of each other.
teries were placed, F flag over the spot, T tunnel or heading, C one of the chambers, L R level of proposed railway, L W level of low water.
Fig. 2.-Section showing the movement of the mass.
Fig. 3.- Plan showing the projection of the cliff; the heading T, and chambers A in which 50 barrels of gunpowder were placed, B 70 barrels, and C 60 barrels.-Civil Engineers and Architects' Journal.
SUGGESTIONS UNDER Captain FitzRoy's New Bill, for the better regulation of
Ship-masters, with security of Owners and Underwriters. [We consider the following worthy of special attention, and think our corres
pondent should follow up the subject, illustrating his statements with cases in
point.] Sir.-As you have given place in your last month's number, to my "Suggestions relative to Ship-masters, salvage, &c.," I am induced to add a few more suggestions; the general bearings of which I leave for the consideration and discussion of your readers, should you deem the matters animadverted upon, worthy of publicity. Firstly, to making wages and disbursements of the master, recoverable on the ship, when arrived at home only, in the same way as the rest of the Ship's company. Many objections, I am aware, can be taken ; but as the law now stands, there are no means for the masters coming under cognizance of the Court of Admiralty. The masters redress is a personal one against the Owner, and the latter has no cheap means for exposè or punishment, and which together induce dishonest and heartless minded masters, to help themselves in various ways, to any extent, and even upon the ship herself, coute qui coule, aware that they have no other security than against the Owner personally, and vice versa. The consequences of this, to my certain knowledge, have been, that when they choose to entertain doubts right or wrong, of their Owners responsibility, they set the agents at defiance, and act as they think fit, with ship and earnings, at any sacrifice and results; and for which an Owner may perhaps once in his life, be foolish enough to prosecute, if he can catch the master. But as this makes the loss and injuries greater, they are generally allowed to go their way; they proceed to other outports or to London, make up a case with references should they be pressed, and secure a fresh ship by gratuity to a Broker or Ships' auctioneer, and by the further incentive of taking £1 , „ per month under current wages. I can cite five instances of the above kinds of a ruinous and infamous nature, which have occurred in the southern colonies within the last eighteen months! To legislate in detail for these cases would be futile. I allude to them to shew the necessity for great caution and investigation, and powers by the Boards proposed, under Captain FitzRoy's new bill, powers to require of masters and mates themselves to produce written certificates, &c., from their employers during the last seven years, and for the Boards to make secret inquiries, and to take evidence, &c. viva voce or by declaration ; for without these powers it will be found not only difficult to arrive at the truth and real merits generally (which are quite as essential as the Nautical abilities), but upon open application to the referees A. B. C. of the applicants, information will be withheld under doubtful cases, out of false sympathy or fear of trouble and annoyance.
Certainly it is better that, if the applicant cannot produce written testimonials, and the other general proofs to be required in support of other representations be not fully and satisfactorily adduced and supported, the rejection should be fearlessly decided on; rather than Owners, Shippers, Underwriters, Emigrants and others, should be deceived by commiting their property and lives to the care, custody and integrity of the doubtful men!
We have Lloyd's registry and classification of ships, why not of the masters, This would give second rate men a chance of employ, by those who thought fit, whilst third rate men might pass perhaps, as mates of 1st or 2nd class, and