The works were conducted under the direction of Colonel G. G. Lewis, R.E., with Captain E. C. Frome as his executive officer. In the face of the cliff, about thirty-five feet above high-water mark, a nearly horizontal gallery was cut a considerable distance into the chalk. The mouth of this gallery was approached by a ladder and platform, supported by scaffolding. Inside the opening a cave was formed for spare tools and materials, and another also was excavated at the end of the gallery for a similar purpose. At right angles from this gallery, extending fifty-five feet to the right and sixty-five to the left, were corresponding galleries, at the extremities of which were two chambers of about seven feet cube, containing 12,000 lbs. of powder each. Two wires, respectively in connexion with two of Grove’s batteries, completed the arrangements for exploding these charges simultaneously. The chambers of powder were about seventy feet from the face of the cliff, and were intended to drive out its under portions and roll them towards the sea. Upon the surface of the rock, eighty-four feet from its edge, were sunk five vertical shafts, at the bottom of which other chambers were excavated, containing, in three of them, each 600 lbs. of powder, to be fired simultaneously with the two great charges. The two other chambers were not loaded, from the non-arrival of a sufficient quantity of powder. The shaft chambers were connected by wires to a Smee’s battery, placed in a wooden shed erected about 180 feet from the edge of the cliff. The wires to convey the electric fluid to each chamber were covered with tape and varnished or tarred over. The galleries were tamped with sand and chalk, in bags, to within fifty feet of the mouth, both branches being tamped up, and twenty feet down the large gallery. “The men worked in reliefs for the whole twenty-four hours. For the gallery three reliefs of four men each, were appointed; and subsequently for the branches three reliefs of six men for the two.... The relieving hours were 6 A.M., 6 P.M., and midnight, except at periods when the high spring tides prevented the relief passing a projecting part of the cliff at the proper hours, when arrangements were made to equalize the extra time the men were so employed.... The work was hardly ever interrupted in its progress, for by compelling each relief to be in barracks six hours before their turn came for work, the men were invariably fresh at the commencement of their time; and as the working pay was good and the best miners were always employed, the average amount of work performed by night equalled that accomplished by day.”
All the necessary operations being completed, the great explosion, on a signal from the galvanic battery by sergeant Edward Wright took place on the 19th September, under the immediate orders of Colonel Lewis. The effect of firing the two great chambers was to throw out the under portions of the rock, which, from the downward pressure of the superincumbent masses, rolled with a convulsive heaving towards the sea, carrying with them the three smaller chambers unexploded, and causing deep fissures in the chalk as far back as the very foundation of the battery shed. The undertaking, so far as dislocating an immense mass of chalk from the cliff was concerned, was thus perfectly successful; but subsequent experience has thrown doubts upon its utility as a breakwater, for the chalk is gradually being washed away, and if some natural intervention does not take place to conglomerate the mass into a compact resisting body, time will remove the headland altogether, and expose as before the land and its defences to the gradual invasion of the sea.
The explosion was one of the largest that had ever occurred, and passed off without accident, delay, confusion, or inconvenience to any one of the detachment engaged, or to the thousands of spectators who witnessed the operation.[[48]] The quantity of chalk displaced was about 200,000 cubic yards, or about 292,000 tons. The distance the debris was hurled in front of the original line of cliff was more than 300 feet. The average breadth of the mound formed was about 360 feet, and its mean height about 50 feet.
Much of the expense of the service was paid by Mr. Catt, jun., a miller, to whom the surrounding property belonged, and who, as well for his own interest as for the welfare of Newhaven and its harbour, undertook a large share in the liability. The total cost of the work was 907l. 12s. 11½d. Of this sum only 92l. 3s. 1d. was spent on sapper labour, which included their services for levelling the ground, and other preliminary duties, excavating the galleries, shafts, and chambers, digging a trench above the cliff, loading and tamping the mines, making surveys and sections of the cliff and the works, preparing and laying wires, clearing away the debris, and various other miscellaneous duties, which the extensive and peculiar character of the operations rendered essential.
Lieutenant-General Sir John Burgoyne, the inspector-general of fortifications, Lieutenant-General Sir Charles Pasley, and a number of officers of royal engineers, were present to witness the explosion. Later in the day the non-commissioned officers and privates commemorated the success[success] of their exertions with an excellent dinner. “Night and day,” wrote Colonel Lewis, “the detachment worked with great zeal and alacrity, exposed to colds from draughts and alternations of temperature, and to injury from falling masses. Nevertheless, no material accident occurred to any one, and all gained the praise of their officers, and the respect of the inhabitants of Seaford for their courteous behaviour and good conduct.”[[49]]
The observations made with Airy’s zenith sector for the determination of the latitudes of various trigonometrical stations used in the ordnance survey of the British Isles, which commenced in 1842, terminated in December 1850, and the results have become the subject of an important volume from the pen of Captain Yolland, R.E. The instrument at first was in charge of officers of the corps, but in course of time, from a paucity in their number, it devolved upon corporal, afterwards sergeant, James Steel. The first man of the sappers honoured with the use of the instrument was private Benjamin Keen Spencer,[[50]] who was employed with the earliest parties in carrying on the observations; and it is not a little curious to add, that General Colby directed his own personal observations, the work of his most able days to be tested by sergeant Steel. This is a striking proof both of the greatness of his mind, and his freedom from those petty jealousies which sometimes mar the superiority of distinguished characters.[[51]]
The following table (p. 48), taken from Captain Yolland’s Sector Volume, “shows in a condensed form the stations observed from, the period during which the observations were in progress, the officer of royal engineers, or non-commissioned officer of royal sappers and miners in charge of the instrument, and the strength of the party; also the number of nights on which observations were made, and the number of observations registered at each station.”[[52]]
| Stations | Observations in progress. | Officer or non-commissioned Officer in charge of the Instrument. | Strength of the Sappers. | Number of Nights on which Observations were made. | Number of Single Obserations. | ||||
| From | To | ||||||||
| South Barule, Isle of Man. | } | 11 Oct., 1842 | 12 Oct., 1842 | { | Lieuts. Hornby and Gosset | } | 6 | 2 | 113 |
| Blackdown, Dorset | 26 Nov. ” | 1 Jan., 1843 | Ditto | 7 | 20 | 1087[[53]] | |||
| Precelly Mountain, Wales | } | 11 Apr., 1843 | 10 May ” | { | Lieuts. Hornby and Luyken | } | 5 | 17 | 674[[53]] |
| Forth Mountain, Wexford | } | 29 May ” | 17 June ” | Lieut. Hornby | 7 | 12 | 659 | ||
| Hungry Hill, Co. Cork | } | 30 June ” | 31 July ” | Ditto | 7 | 9 | 295[[53]] | ||
| Feaghmann, Co. Kerry | } | 14 Aug. ” | 26 Aug. ” | Ditto | 7 | 9 | 395[[53]] | ||
| Tawnymore, Co. Mayo | } | 2 Oct. ” | 14 Oct. ” | Ditto | 2 | 7 | 294 | ||
| S. End of L. Foyle Base | } | 8 Nov. ” | 15 Nov. ” | Ditto | 2 | 6 | 335 | ||
| Monach, Stornoway | 16 June, 1844 | 3 July, 1844 | Lieut. Gosset | 5 | 10 | 180 | |||
| Ben Hutich, Sutherlandshire | } | 5 Nov. ” | 24 Nov. ” | Ditto | 6 | 10 | 480 | ||
| Hensbarrow, Cornwall | } | 9 June, 1845 | 14 June, 1845 | Corporal Steel | 4 | 6 | 290 | ||
| South Barule, Isle of Man | } | 21 July ” | 5 Aug. ” | Ditto | 3 | 2 | 114 | ||
| Ben Lomond | 2 Sept. ” | 4 Oct. ” | Ditto | 4 | 11 | 635 | |||
| Ben Heynish, Isle of Tiree | } | 11 Nov. ” | 28 Dec. ” | Ditto | 4 | 10 | 267 | ||
| Week Down, Isle of Wight | } | 26 Apr., 1846 | 17 May, 1846 | Ditto | 4 | 11 | 556 | ||
| Dunnose, ditto | 24 May ” | 6 June ” | Ditto | 4 | 13 | 643 | |||
| Boniface Down, ditto | } | 13 June ” | 21 June ” | Ditto | 4 | 7 | 356 | ||
| Port Valley, ditto | } | 28 June ” | 14 July ” | Ditto | 4 | 10 | 411 | ||
| Saxavord, Unst, Shetland | } | 3 Oct. ” | 26 Jan., 1847 | Ditto | 4 | 20 | 566 | ||
| Gerth of Scaw, ditto | } | 16 Feb., 1847 | 10 Apr. ” | Ditto | 4 | 21 | 581 | ||
| Balta, in Shetland Isles | } | 30 Apr. ” | 13 July ” | Ditto | 4 | 20 | 732[[54]] | ||
| Cowhythe, Banffshire | } | 7 Aug. ” | 27 Sept. ” | Ditto | 4 | 18 | 641 | ||
| Southampton | 21 Oct. ” | 4 Sept., 1848 | { | Sergt. Steel and Corp. W. Jenkins | } | 2 | 180 | 8730 | |
| St. Agnes, Scilly | } | 13 May, 1850 | 1 June, 1850 | Sergeant Steel | 4 | 11 | 418 | ||
| Goonhilly Down, Cornwall | } | 25 June ” | 28 July ” | Ditto | 4 | 9 | 442 | ||
| North Rona, Co. of Ross | } | 11 Sept. ” | 16 Sept. ” | Ditto | 4 | 5 | 428 | ||
| Great Stirling, Aberdeenshire | } | 14 Nov. ” | 6 Dec. ” | Ditto | 4 | 9 | 439 | ||
“The list of stars,” says Captain Yolland, “selected for observation fell within the parallels of declination of 37° 38´ and 69° 54´. About two-thirds of this number were originally chosen, so as to admit of a continuous series of observations being made when the weather proved favourable throughout the night, and two observers were for some time employed with the instrument, who relieved each other after an interval of several hours’ work. The observations were frequently carried on continuously for upwards of eight hours, but six hours’ constant observing was reckoned a good night’s work for one person, in consequence of the fatigue caused by his having to ascend twice to the table to make each complete or double observation.”[[55]] In the course of the service additional stars, not originally selected for observation, were occasionally observed, some of which were not found in the works of the best authorities.[[56]] Two men, ready penmen, were also employed in booking, and afterwards copying, the observations on the skeleton forms, for transmission to the map office at Southampton, where the necessary computations in connection with the observations, were carried out and completed under the direction of Captain Yolland, R.E.
It would be out of place here to make any copious detail of the employment of the sappers on this special duty, belonging as it properly does to the history of the operation, and being so amply recorded in Captain Yolland’s Sector Volume; but exception may fairly be taken to a few particulars in the personal services of the sergeant, which may prove interesting to the reader, and induce other non-commissioned officers in the corps to render themselves not only useful to their officers, but to deserve, in executing any important duty for which they may be selected, their confidence and approbation.