1842] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



69 



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. CuUtt 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 irresistible influence of Plulus and 

 Pluto combined, curlseyed down to meet the reluctant embraces of 

 astonished Neptune, 1 need only mention that the flagstaff, which was 

 standing on the summit of the cliff before the explosion took place, de- 

 scended 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 had by its acquired velocity slid past it. 

 and left comparatively 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 of! 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 perhaps 8 or ten cubic feet, although we observed a vast 

 number of blocks, which contained from two to three cubic yards and up- 

 wards, one of which was driven some distance into the Shakespeare 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 explosi n 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 dimen- 

 sions of the mass, which were given as under 300 feet in height by, say 50 

 feet longer than ihe 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 291,686 cubic yards, from this is to be deducted 

 50,000 yards, the estimated quantity to be now shifted in forming the road, 

 we shall then have 30,000 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 months' work, and £7000 expenditure was effected 

 by this blast. Now allowing Sd. 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 ~l\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 pre- 

 viously, no doubt brought about by the infiltration of water more than 

 the sapping of the base by Ihe 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 zigzig 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, be one of difficult 

 remedy. It also becomes a matter of interesting inquiry as to the effect 

 which a lesser qantity 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 j" 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 ope- 

 rations. 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 other, far more distant, 

 it w as clearly perceptible. Thus where the batteries were placed, those in 

 charge of them thought the charge had missed fire, from their being insen- 

 sible 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 clill it was very 

 evident that the shock was felt by some and not by others, though standing 

 within a few yards of each other.] 



Fig. 1.— Section of the Cliff. 



Fig. 2. — Section showing the movement of the mass. 



Reference. 



Fig. 1.— Section of Cliff before the explosion ; H house In winch the bat- 

 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 clifi ; the heading T, and 

 chambers A in which 50 barrels of gunpowder were placed, B 70 barrels, 

 and C 60 barrels. 



Neapolitan Steamers. — We lately had the pleasure of attending the 

 trial of two steam vessels, named the Jimidine (Swallow), and the Antelope, 

 built at N'orthflect, by Mr. Pitcher, for the revenue service of his Neapolitan 

 majesty. The engines of both vessels are manufactured by Messrs. Boulton, 

 Watt, and Co. These vessels arc of similar dimensions, in fact built from 

 the same drawing, and are in length between perpendiculars, 100 feet ; keel 

 for tonnage, 90 feet, 5 inches; extreme breadth, 16 feet; moulded breadth, 

 15 feet 5 inches; depth in hold, 9 feet G inches; tonnage, O.M., 123^-J; 

 displacement as launched, 65 tons; ditto, complete with 23 tons of coals, 

 145 tons. Draftj at this, 7 feet 3 inches. Immersed section, 91 feet. Speed 



