PRISMATIC CLINOMETER. 23to &th of a11 inch fall of the mercury in an ordinary barometer tube. The total fall was therefore equal to &ths of an inch (equal to 0,0416 inch ;) and as the height of the second floor above the basement, was found by actual measurement to be 35 feet, this'agreed very well with the ordinary rule, namely that -,$th of an inch fall, corresponded to about 85 to 90 feet difference of altitude, according to the conditions of the at~nosphere at the time.

SOUTH COAST OB ENGLAND. 205Mr. REDMAN, in answer to questions by Mr. Walker, explained, that the authorities he had consulted, for the present state of the outline of the coast, were the Admiralty charts, and the Ordnance and other modern maps of acknowledged accuracy, and as far as was practicable, he had verified the topographical correctness of those documents, by personal inspection, having walked over, and carefully examined the whole length of coast described, for the purpose of preparing the paper submitted to the Institution. He had already given in the paper, the ancient authorities, and he had spared no expense, or trouble in obtaining access to the earliest maps and the works of the best topographical writers, as the subject was of vast importance in marine engineering, especially in reference to the construction of harbours and coast-works of defence ; and he submitted, it was most desirable, that such natural agencies, as had been described, and the instances of the compensating effects of alternating loss and gain, should be correctly understood.Mr. NEWTON directed attention to the recently-exposed remains of the Roman castrum, at Lymne: it might be presumed, that at one period, that building had been situated on the shore ; and that the high lands at the back, being filled with springs, not drained away by any agricultural operations, had caused an ext.ensive landslip, whereby the castle walls were carried bodily forward for some distance, altering the line of the coast and occasioning a deposit from the river, which probably debouched near it.' I t was worth investigation, whether the first accumulation at Dungeness, might not have been originally formed by a somewhat similar occurrence.Sir WILLIAM CUBITT, said, that at Rye he had counted twenty distinct ' fulls ' of shingle ; he apprehended that these ' fulls' coincided with, or at least were influenced, to some extent, by the lunar cycles. H e would throw out the suggestion for the consideration of those who had more leisure for observations of that kind than he had, as the question was one of great interest, both theoretically and practically. H e was of opinion, that Winchelsea Castle was originally built close to the sea, as the ' fulls' now extended from the Castle to the present high-water mark.Sir CHARLES LYELL had derived much practical information from the interesting paper just read : particularly from the portions treating of Hurst Point and the Chesil Bank, to which he had devoted some attention. T h e effect of recent storms, on these parts

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said, that the cost of the dock walls per lineal yard, including excavating, piling, and masonry was ~€110 ; the cost of a pair of gates, at 25s. per square foot,, exclusive of the machinery, was %2,300 ; and the reclaimed land, on the foreshore of the Humber, was purchased from the Government,, by the Manchester and Sheffield Railway Company, for $30,000. The timber used in the construction of the cofferdam and exterior works of the enclosure amounted to 709,000 cubic feet, of which 410,572 cubic feet were required for the cofferdam alone. The cost of the cofferdam was $70,000, being at the rate of 246. 10s. running foot. The total ex enditure on the Great Grimsby ocks was about $1,050,000.8 f this sum $112,207 was for the purchase of the old dock and outfall, while the remaining amount, $937,793, was expended on the construction of the docks and the reclamation and purchase of land, no interest on capital being included in these amounts. H e wished to bear testimony to the great value of creosoting for the preservation of timber. H e had lately examined the tidal pier, and had observed, that some of the uncreosoted piles, which were originally 14 inches square, were now wasted considerably, had lost half their thickness, and were merely hanging by the bolts ; whereas the creosoted timbers were as sound as when first driven.Mr. COODE remarked, with reference to the threatened breach t.hrough the Spurn Point, that he considered the preservation of the promontory was of paramount importance to the harbour and port of Grimsby. The Board of Trade had, some time since, referred t,he matter to him, and he had recommended the construction of timber groynes upon the beach facing the North Sea. Some of these groynes bad been executed, and the consequent accumulation of sand and gravel had been so rapid, that the Spurn Point was already materially strengthened.It was the intention of the Government to complete the remainder of the groynes in the ensuing spring.Sir EDWARD BELCHER, in allusion to the danger to be apprehended from the removal of Spurn Island, said, that the true bearing of the Spurn Point from the dock entrance was about N. 68' E. ; and on this bearing alone, the sea-wave would enter into the outer entrance,-that was, provided nature offered no other obstacles. H e was one of the naval advisers of the late Mr. Rendel in 1850-52, and he found, hy the later Admiralty Surveys, corrected up to 1S60, that his views, as expressed in 1850-51, had been realised. H e had then stated, that " for every foot you advance into the deep water, if carried obliquely-not stubbornly at right angles, in opposition to the t.idal course, at half or three-quarters ebb-nature will accompany you by a deposit covering the channel, which would probably be scoured by the land-drains." From Mr. Calver's survey of 1851-

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