1847.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



361 



can Lakes there are also terraces at various elevations, corresponding 

 witii the more remarkable elevated beaches iu Britain. In conclu- 

 sion, the author observes that these phenomena cannot bea ccounted 

 for by supposing a number of distinct and local disturbances; but imply 

 an equable elevation of the land (or subsidence of the sea) simultaneously 

 over large areas: and he points to the plains of South America described 

 by Mr. Darwin in proof of the occurrence of such uniform elevations. 



Remarks. — Air. J. Phillips remarked that those who had accepted Mr. 

 Darwin's or Mr. Hopkins's views of the nature and mode of the force by 

 which tracts of laud were elevated would believe that the surface of an 

 elevated tract must incline from an axis, or point of greatest elevation. He 

 considered many of Mr. Chambers's raised beaches, such us those of Brent 

 Knoll and the Gloucestershire valleys, had in reality been produced by the 

 removal of softer beds of horizontal rock, and that as many terraces would 

 be found as there were alternations of hard and soft materials. 



Prof. Sedgwick contended that it was extremely improbable that the 

 elevation of the land had taken place so uniformly all over England as 

 described by Mr. Chambers ; much less, that France and Norway and 

 America would be raised the same number of feet at many successive 

 periods. The elevation of the bed of the sea and ils conversion into dry 

 land had taken place repeatedly from the earliest to the latest geological 

 periods ; and strata were found in every kind of position, inclined, vertical 

 and contorted, and seldom horizontal over any wide space. 



Sir H. De la Heche observed that in pursuing this inquiry the author 

 should be careful to ascertain that the terraces were really raised beaches, 

 formed in the ordinary way by the action of breakers on a coast. At Bath, 

 there were certainly no indications whatever of the sea at various levels on 

 the bills. 



Prof. Lyell described the elevated beach-lines around the American 

 lakes as being sometimes in the form of hills of sand and sometimes of low 

 cliffs. Allowing for these changes in character, they might, perhaps, be 

 traced for hundreds of miles, and had been seen on the opposite shores of 

 the lakes. With respect to Norway and Sweden, where raised beaches 

 were numerous and well marked, observation had shown that whilst the 

 northern provinces were still rising the southern were actually subsiding. 



Prof. J. Forbes stated that external form was not suflicieut to determine 

 the existence of an elevated sea margin. All instances should be excluded 

 Tvhere there was not an actual section to show the nature of the terrace or 

 deposit. Much difficulty would also be experienced in determining the 

 mean level of a well-defined sea beach. The limit of doubt could not be 

 within six feet above or below the line chosen ; and as in Mr. Chambers's 

 sections there were nine sea beaches, eight of them under the height of 280 

 feet, and three intercalary beaches besides, there was only an interval of 

 about twenty-five feet between each. It became physically impossible to 

 identify distant beaches where the levels were so ill-defined and the beaches 

 themselves so numerous. If the intervals had been very irregular, the 

 comparison of one series with another would have been much more satis- 

 factory. The terraces on the banks of the Alten Fiord were found at heights 

 decreasing in such regular progression that he was convinced they were 

 only portions of one terrace sloping gradually away. 



Mr. Darwin referred to the prairies of North America and the great 

 plains of Patagonia and the Pampas of South America in support of Mr. 

 Chambers's view of the occasional uniform elevation of large tracts of 

 land. The raised beaches in the Andes occurred at irregular intervals to a 

 height exceeding SOU feet, and maintained a uniform level for great dis- 

 tances. 



Mr. Chambers, in reply, stated that he had necessarily omitted a great 

 portion of the details In his paper, which would have explained or supported 

 tlie particular cases, and had tiuowu out his general views to invite dis- 

 cussion and further inquiry. 



PROCESDINGS OF SCIENTIFIC SOCISTIIIS. 



INSTITUTION OF CIVIL ENGINEERS. 



Jniie 29. — The President in the Chair. 



This was the last meeting of the session, and several papers were read 

 in abstract because there was not time for giving them in exlens). 



The first was " On the Advantages and Economy of maintaining a high de- 

 gree of Cleattiiucss in Enads and Streets ; with an account of the Construction 

 and Operation of the Street-sweeping Machine." By Mr. J. M hitwobth. 



It treated of the general advantages of street cleanliness, the comfort of 

 the pedestrian, the avoidance of impurity to the air from the decomposition 

 of dirt on the pavement ; less dirt and dust being carried into the houses, a 

 saving in the cost of maintenance of roadways, and a diminution of the 

 draught of carriages. The annoyances of the common method of cleansing 

 were then detailed — with the importance of employing plenty of water in 

 the cleansing of streets, to liquify the mud, to cause the dirt to swell and 

 rise from between the stones, to cool and purify the air during hot weather, 

 and to prevent the dust from being driven into the dwellings. It then 

 showed how much economy there resulted from having force enough to 



cleanse the streets thoroughly and simultaneously in wet weather, par- 

 ticularly by Whitworth's sweeping machine, which is a cart drawn by one 

 horse and managed by one man ; it has on one of the wheels a toothed 

 wheel working into a pinion, which gives motion to a drum over and 

 around which passes two endless chains passing also round another 

 drum at the lower extremity of a light frame suspended at the tail of 

 the machine, over an inclined plane depending from the drum frame; 

 these endless chains carry a series of broad brushes formed of an Indian 

 rush of peculiarly elastic nnd durable nature ; they travel at a velocity de- 

 pending upon the speed of the horse, and impinging upon the ground with 

 a force which is regulated by a coiled spiral spring, carrying the dirt up 

 the inclined plane into the cart, whence it is emptied when the receptable 

 is full. 



The next paper read, was " An account of the sea defences of Romney 

 Marsh, commonly known by the name of Dynichurch Wall, and the probable 

 origin of the Marsh itself, or the manner in which it was reclaimed from tlte 

 Sea." By Mr. James Elliot, Juu., the resident engineer. 



Romney Marsh, properly so called, forms a triangle, the base of which 

 would be a line drawn from Romney to Appledore, and the apex at Hythe, 

 and comprises about 24,000 acres. It is probable, that this marsh was 

 caused in the first instance by the formation of a natural barrier of shingle, 

 nearly where Dyinchurch Wall now stands, by which the sea was ex- 

 cluded, and that the first artificial works were executed by the Romans, 

 when they held possession of (lie country. They consisted of the erection of 

 cross walls running from the natural barrier (the " Full") to the hills, at 

 the base of which the ancient river Limene ran. The chief of these (the 

 Rhee Wall), ran nearly iu a straight line from Romney to Appledore, and 

 it was at that spot where probably the main work was peri'ormed. 



Upon the supply of shingle from the west being cut off by the extraordi- 

 nary accumulation at Dungeness Point, the natural barrier at Dymchurch 

 gradually became weakened, and it was necessary to take some steps lo 

 prevent its total destruction ; the first measure adopted was the erection of 

 an inland wall at some little distance, at the back of the " Full," and 

 afterwards, the construction of large stone groins on this point or sea-side, 

 at right angles to the line of coast, in order to increase the deposit of 

 shingle. However, as the supply of shingle gradually decreased, on ac- 

 count of the constant movement to the eastward, and as all that escaped in 

 that direction was permanently lost, these means were found insufficient, 

 and a system of *' arming," with brushwood and timber-piling was adopted. 

 This was found to answer the purpose for a considerable period, but it also, 

 in the course of time, gradually became insufficient; and it was found ne- 

 cessary, at length, after numerous experiments, to adopt a stone facing 

 with an avei'age slope of about eight to one, up to high-water mark, gra- 

 dually increasing in steepness fiom that point, and terminating in a curve 

 of seven feet radius. "The stones, which were laid in a bed of concrete, 

 where they were most affected by the waves, were of different sizes, aver- 

 aging from eighteen to six inches in depth, the largest of them being in the 

 middle, where the greatest wear and tear took place, and at which place 

 rows of sheet piling were also driven for additional security. 



This plan was adopted by the author after mature deliberation on the 

 reports of Mr. Rennie and Mr. Walker, and a very careful examination of 

 the locality. Part of the wall has now been standing for ten years, and has 

 required a very trifiing amount of repair, while the annual expen.-e has been 

 reduced from 10,000/. to 4,000/., with every prospect of a still further re- 

 duction being effected, as upwards of two-thirds of the work are now per- 

 manently completed. 



The last paper was, " On Ocean Steam Navigation," by Captain Hen- 

 derson, calling attention to the fact, that iu this great maritime nation, 

 naval architecture was neglected as a science, as was proved by the ex- 

 perimental squadrons and some of the ordinary steam vessels lately built. 

 Neither the public nor science had derived any advantage from these costly 

 experiments, owing to the absence of any information, in a systematic 

 form, that correctly described the relative size, capacity, resistance, power, 

 or speed of steam-ships ; the present tonnage and nominal horse power, for 

 all purposes of analogy, being quite fallacious. 



The meeting was then adjourned until the second Tuesday in January, 

 1848. 



ROYAL INSTITUTE OF BRITISH ARCHITECTS. 

 June 28. — C. Fowler, Esq., V.P., in the Chair. 



Dr. Bromet, F.S.A., exhibited a Drawing of a Templars' Church of 

 the twelfth century, at Metr, having an octagonal nave with a pyramidal 

 roof, and a semicircular apsis with a semi-conical roof; — also a Drawing 

 of a Twelfth Century Church at Mathieu, near Caen, showing an arch 

 between the nave and choir of elliptical form, and ornamented with three 

 rows of counterset chevrons. 



A Letter was read from Sydney Smirke, Fellow, on some peculiarities 

 in the Architecture represented on the Bas-reliefs recently brought from 

 Nimroad, and now in the British Museum. 



A paper was read : — " A Sketch of the professional life of George 

 Dance, Architect, R.A.," by Samuel Angell, V.P. 



The Premiums in Books awarded in the Students' Class at the previous 

 General Meeting were presented as follows: — 



To Mr. W. BooTCHEK, for the best Series of Sketches of Designs from 



Subjects given monthly by the Council, — a Copy of Chambers' Treatise 



