1843.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



165 



BLASTING OF THE ABBOTS CLIFF AT DOVER. 



Another of those remarkable engineering operations which have already 

 attracted the public attention, in connexion with the South Eastern Railway, 

 took place on Tuesday. April 18th, at a distance of about three miles to the 

 westward of the town of Dover. In order to afford an outlet to the Abbot's 

 Cliff Tunnel, and a platform on which the rail could be laid down between 

 that and the Shakspeare tunnel, it became necessary to remove a portion of 

 the projecting cliff. From the success that had attended former operations 

 of the kind, and especially the recent blast at Rounddown Cliff, it was re- 

 solved to remove it by the aid of gunpowder. 



The surface of the cliff acted upon by this explosion lay to the westward 

 of the Rounddown Cliff, and its remaining cliff forms the face of the ter- 

 minus of Abbot's Cliff tunnel. It extended 300 feet in length, and the height 

 of that portion which was directly acted upon was 200 feet. The object of 

 the operation was to slice off. as it were, a large portion of this surface, so as 

 to make that which was before rugged and uneven, and which projected far 

 too much in the way of the proposed line along the side of the cliff, perfectly 

 flat and smooth, and fit to afford a sufficient platform for the road to be laid 

 down upon, and to prepare the terminus of the tunnel. The "slice"' to be 

 removed varied in thickness, according to the extent to which the surface 

 projected beyond that which would be convenient to the operations ; at some 

 points it was 60 feet, and at others 30 feet, and the quantity of powder in- 

 troduced at the different parts was, therefore, proportioned to the thickness 

 of cliff to be removed, regulated, of course, by the degree of resistance 

 which, from the greater or less nearness of the surface to the chambers in 

 which the powder was deposited, would be offered to the action of the pow- 

 der. The quantity of powder in each chamber was calculated according to 

 the line of least resistance. Cubing the line of least resistance, one-half the 

 number of feet is the number of ounces of powder used. The arrangements 

 made for the introduction of the powder and the simultaneous ignition (if 

 possible) of the different charges were simple, and, at the same time, inge- 

 nious in the extreme. There were altogether 100 barrels of powder, or 

 10,0001b. This quantity was distributed in various proportions in 15 different 

 chambers, at nearly equal distances. To form these chambers the rock was 

 perforated at those nearly equal distances, and the different proportions of 

 powder were introduced on Saturday last, and "tamped up'' close. There 

 were two separate lines of these chambers of powder, and therefore two 

 series of charges ; one being near the top of the cliff, about 200 feet from 

 the summit, the other about 100 feet lower down. Thus a space of about 

 150 feet from the bottom of the cliff remained altogether untouched by the 

 explosion, that being required as a platform for the road to run upon at the 

 entrance of the tunnel. The apparatus for igniting these different charges 

 was placed to the eastward, about 2000 feet from the nearest, and about 500 

 feet from the furthest chamber. It consisted of six batteries of 20 plates each, 

 and by an ingenious invention of Mr. Hodges, the assistant to Mr. Wright, 

 the resident engineer of the line from Ashford to Dover, they were all fired 

 simultaneously. Simple as the invention is, it is not so easy to describe it on 

 paper. Suppose a triangular skeleton chair ; what would be the seat of it 

 is suspended by a common string at the distance of about an inch or more 

 from a framework beneath (resting on the legs of the chair), in which are 

 fixed the batteries and connecting wires. Immediately under the string 

 which suspends the other poriion of the battery is placed a circular trough, 

 in which there is a "blue" light. Through this light is passed a fuse, 12 

 feet long, and taking some minutes to burn down. This fuse was fired by Mr. 

 Hodges, who had time to get away from the spot before the string was burnt. 

 The moment the string w : as severed by the flame, down went the upper 

 framework, the voltaic action was performed, and the electric fluid commu- 

 nicated to the wires. These wires were two, one for the upper, the other for 

 the lower range of chambers, each extending the whole length of the surface 

 to be operated upon, and attached to them were other supplementary wires 

 communicating with the chambers of powder. The ends of these additional 

 wires were of course formed in the usual way, with a piece of platina wire 

 affixed, which on ueing made red hot by the electric fluid ignited the gun- 

 powder in what are called the bursting charges— small portions of powder in 

 cases surrounding the ends of these wires, which again immediately fired the 

 larger quantities of powder contained in the different chambers. 



Thus within a few moments after the ignition of the blue light, the upper 

 framework of the skeleton chair above described fell down, the voltaic action 

 was completed, and in almost an equal period of time the explosion was 

 effected. And yet how remote to all appearance the connection between the 

 turning of a short piece of string (a foot long) and the fall of that immense 

 mass of cliff! 



The operations at the Rounddown cliff were carried on under the advice of 

 General Pasley and Lieutenant Hutchinson, who also took a great interest 

 in the proceedings on the present occasion ; but the whole of the arrange- 

 ments for the explosion of to-day were under the controul of Mr. Wright, 

 the engineer, assisted by Mr. Hodges, as already mentioned. As far as the 



practical effect of the operation was concerned all was successful ; but as a 

 mere sight the affair was unfortunate, in consequence of the thick fog that 

 hung over the cliff, and made it impossible to see the arual fall. 



At 4 o'clock, the hour appointed for the blast, many thousand persons 

 were collected to witness it, but the thick fog obscured all. I took a beat, 

 and approached as near to the shore as was allowed, but could see no more 

 than the crumbling mass falling down into the water beneath with a sound 

 resembling the roar of artillery beard at a distance, and the noise of the surge 

 breaking on the sea shore. In respect of the noise created, this explosion 

 differed from that at the Rounddown Cliff. There no noise whatever was to 

 be heard, or scarcely any, and the mass of r..ck glided almost silently into 

 the sea like a mighty wave ; but in the Abbot's Cliff blast there was much 

 more noise, and it was more prolonged. 



Those who were on the cliff were sensible of a shock a few moments before 

 the detached portions of the cliff fell. Explosion is an inappropriate term to 

 use ; for, in fact, as far as hearing is concerned, there is nothing of the sort ; 

 —the operation of the powder is internal, and the effect only known by the 

 fall of the fragments. Mr. Hodges, the assistant engineer, fired the fuse 

 in connection with the battery. He had four minutes in which to get away, 

 but had calculated that he could run down the ladder in two and a half. He 

 was the last person who left the range of the batteries. 



Beside the multitude of persons collected on the cliffs and on the adjacent 

 shore, the sea was covered with boats of all sizes and shapes. There were 

 also two large steam-boats filled with visitors. 



Although in consequence of the thick fog or mist the spectators were 

 deprived of much of the gratification which such a sight would have afforded, 

 the operation, in a scientific point of view, was held to be decidedly success- 

 ful. All the chambers of powder were ignited simultaneously (or nearly so), 

 and the immense mass of disturbed chalk and earth fell slowly and equably 

 into the sea. The exact results, however, cannot of course yet be ascertained. 

 — Times. 



ROYAL ACADEMY. 



Professor Cockerell's Lectures on Architecture. 



(From the Athenmtm.J 



Lecture VI, and last. 



Proportion, and the application of its golden rules, as they affect the ex- 

 ternal forms of architecture, had occupied the latter part of the preceding 

 lecture ; the avaKoyia. of the Greeks, delivered to us by Vitruvius, that ana- 

 logy, by which all the conformations of artificial bodies were derived from 

 natural bodies, seemed to be a principle of obvious importance and utility to 

 the architect, and should be attentively considered. 



It appeared that the animal kingdom furnishes clearer lights for our 

 guidance than the vegetable, because organized nature was more constant in 

 her proportions, and enabled us always to re-establish the whole from a 

 part; thus the hand of a Grecian statue, of the Hercules, the Apollo, or of 

 the Venus, or a fragment of any one of the Grecian orders of architecture, 

 enabled us to restore the whole ; indeed, the proportion by aliquot parts by 

 a modulus, a principle of the Greeks, as explained by Vitruvius, lib. i. c. 11, 

 lib. iii, c. 1, was still practised in India, and seems founded in organized 

 nature. 



Not so in the productions of the vegetable kingdom, fragments of which 

 would never enable us to comprehend the whole : however indebted to this 

 part of the creation for the graces of ornament, and various essential analo- 

 gies, architecture found a less sure guide of proportion in this than in the 

 animal kingdom : in fact, all architecture so derived was anomalous, as the 

 Egyptian and the Gothic, in which no fixed laws of proportion have ever 

 been applied or attempted. Columns or supports might be from five to fifty 

 diameters in height, and were only bounded by possibility. The stunted 

 pollard, the spreading cedar of Lebanon, the aspiring poplar, or the attenu- 

 ated cane, were extremes equally at the disposal of the architect. 



But that guide, which the face of nature furnished to the architect for his 

 external forms and proportions, was wanting for the internal — as of areas, 

 squares, courts, and open places ; or of internal capacities (height as well as 

 area) ; as of temples, halls, apartments, &c. ; in these we must appeal to the 

 relations of reason, purpose, and convention. 



Vitruvius (lib. vi. c. 2, 3, 4, C, lib. v. c. 1, aud c. 2.) gives us the experi- 

 ence of the ancients on this important subject. The Greek forum, says he 

 was a square, but the Roman was three by two, because the gladiatorial, 

 shows were exhibited there ; courts should have the proportions of five by 

 three (the favourite of the learned Palladio), sometimes three by two, or 

 sesquialteral, or the diagonal of the square will Ue the length. lie lays 

 down the proportions of all the apartments of the Greek and Roman house : 

 atria, aire, tablinium, and peristylium, triclinia, ceci, exedrai et pinacotheae. 

 He does not, however, establish any principle, and his rules are wholly em- 

 pirical. But the great Alberti, not content without a principle, adopts the 

 Pythagorean doctrine of universal harmony, aud agreement between sounds 

 and numbers, namely, that what pleases the ear pleases also the eye ; he lays 



22* 



