340 



THE Cn IL ENGINEER AND ARCHITECT'S JOURNAL. 



[October, 



cxtiaoidiiiary a |)lace as the Goodwin Sands aie as follow : — the foundation 

 of the column is several feet below the surface of the sand, and is secured in 

 the centre of a stout oak platform, extending from it on eiiher side several 

 yards. This is secured by ujiwards of two tons of pig-iron ballast being 

 lashed to it. In addition to tins, eight stout iron bars, each six feet long, 

 are driven obliquely on each quarter of the colunni, and two also put at a 

 distance of 12 feet on each quarter, and chains attached to them, conimuiu- 

 cating with the upper part of the column and the galler\ . The sands for 

 three or four hours during the tides are high and dry, anil present a fine tract 

 of level extending for several miles. Great numbers of visitors from Rams- 

 gate and Deal attended the erection of this tribute to humanity. The first 

 person to mount it was Lieutenant G. C. Boyes, a young and intrepid officer, 

 wlio, on reaching the summit, hoisted his handkerchief, a fac simile to a 

 union jack. The indefatigable exertions of Captain Bullock, Captain Boyes, 

 Lieutenants Gull and Bowes, and the other officers and men engaged in the 

 undertaking are deserving of the highest praise, they being compelled to 

 work for several hours up to their knees in water. Several visitors afterwards 

 ascended the column, and testified, in the strongest terms, their approbation 

 of this stupendous work for the benefit of humanity. — Times. 



PROCEEDINGS OF SCIENTIFIC SOCIETIES. 



INSTITUTION OF CIVIL ENGINEERS. 



March 31. — The President in the Chair. 



The following were balloted for and elected : — John Crannis Birch, Charles 

 Denrochc, John M'illiam Power, Henry Rawnsley, and George Dobson, as 

 Graduates. 



" On rfclaimincj Land from the Sea, vilh Plans ilhistrathe of Works in 

 Lour/hs Siril/i/ and Foyle." By J. \V. Bazalgette, Grad. Inst. C.E. 



The art of reclaiming land from the sea has been practised from a very 

 remote period. Among the instances best knowni to us are Romney Marsh, 

 in Kent ; the Foss Dyke, in Lincolnshire ; and the coasts of Holland and 

 Flanders. The extreme fertility consequent on such reclamations has caused 

 many attempts to be made, and nearly all have been successful ; but none 

 presents a greater prospect of success than that about to be undertaken under 

 the direction of Mr. Macneil on the borders of Loughs Swilly and Foyle, iu 

 the counties of Donegal and DeiTv. 



Lough Foyle communicates with the Irish Channel by a narrow inlet, 

 above which it spreads over a wide tract of land, and then, suddenly con- 

 tracting, joins the river Foyle aliout four and a half miles below Londonderry, 

 up to which city it is navigable for vessels of 500 or 600 tons burden. The 

 rush of the tide through such a small inlet has carried with it great quantities 

 of alluvial soil, which it has gradually deposited on the side of the lough, and 

 thus formed a bank which extends four or five miles in length, and is only 

 covered by the tide at high water. In order to reclaim this tract of valuable 

 land, of about 25,000 acres, it is jjroposed to construct, somewhat below low- 

 water, an embankment or sea wall, of .ibout 14 miles in length. The tide 

 never rises here above 12 feet, nor is there ever any swell in the lough to 

 endanger the structure. 



Lough Swilly is wider at the mouth which opens into the Western Ocean, 

 and is consequently more subject to the eflfect of wind than Lough Foyle. 

 The highest tides rise about 18 feet. Several embankments are proposed, 

 which v^ill reclaim altogether about 2000 acres of land ; a tract already 

 reclaimed, which is considered to be of the best quality in the counti-y, lets 

 at 5/. per acre. The measurements and soundings to ascertain the best 

 position and requisite depths of the embankments were thus taken. A tide 

 gauge was permanently fixed on which the range of high and low water was 

 marked ; a constaut register was kept of the soundings, and the time at which 

 they were made ; these were afterwards reduced to the high ami low water 

 of any one tide. The distances were determined at the same time, by means 

 of a pocket sextant from the boat, angles being taken between certain fixed 

 objects on the shore, so that the exact soundings could be ascertained and 

 laid down with great accuracy. The slopes of the faces of the embankments 

 vary on the sea face from three or four to one, and two to one on the land 

 side. Each has a culvert 4 feet diameter, with sluices and flood-gates, 

 founded upon piling with tie beams, and the spaces filled with concrete, the 

 whole being covered with planking. The gates are at the lowest level of 

 spring tides, so as to allow of the greatest degree of drainage. The wing 

 walls of squared rubble stone stretching on either side of the gates are founded 

 also on a bed of concrete, 4 feet wide by 2 feet deep. These gates are to be 

 used either to keep back the fresh water for the purposes of irrigation, or for 

 scouring away the silt which would accumulate externally in front of them. 

 A bed of puddle, 4 feet 6 inches wide at the bottom and 3 feet wide on the 

 top, extends longitudinally throughout the embankments. The land water 

 is carried away by a series of catcbwater drains, which extend around the 

 reclaimed lands at the level of high water, having sufficient fall to secure its 

 drainage through the sluices. These drains are puddled, and have their in- 

 ternal faces covered with sods, at an incUnation of two to one. 



As there are many situations where stone is very scarce, and where timber 



abounds, the author has turned his attention to devising a plan of eniljanking 

 applicable to such locaUties. It may be thus briefly described ; the body of 

 the embankment should be of clay, earth, gravel, and stones, dug from' the 

 surface and thrown up in a bank, with a slope suited to the force likely to 

 act upon it. On the water side is placed a strong facing of fascines, Gfeet 

 thick at the bottom and 4 feet thick at the top, embedded in the soil in an 

 oblique direction, the dip being towards the land ; they are securely fastened 

 down by iron screws running at right angles through the whole height. The 

 land face is covered witii sods. In a country where wood abovmds, this kind 

 of embankment woidd be formed at a very cheap rate. In other situations, 

 where the embankments would be subjected to greater strain, the thickness 

 of the mass of fascines should be increased to 13 feet at the bottom and 4 

 feet at the top. In this case, at four feet from the front of the bottom of 

 the slope should be placed a row of fender fascines, 3 feet wide by 2 feet 

 high, bolted down, for the purpose not only of defending the face of the 

 liank from the action of the sea, but for retaining all deposits left behiud by 

 it ; Ijy which means the embankment would in time acquire a natural face of 

 soil, as is the case with some of the endjankments in Holland. The average 

 cost of this kind of embankment, including the sluices and the necessary 

 bed of puddle in the centre, would be about 12/. per running yard. 



This paper is accompanied by seven plans of the proposed embaukments 

 and charts of the loughs. 



" On the use of Mica, as a substilute for Glass, in (he Windows of Work- 

 shops." By Joseph Glynn, F.R S., M. Inst. C. E., &c. 



In the windows of the workshops at the Butterly Iron Works so much 

 glass was broken by the chi])pings of iron, that a substitute was sought which 

 should resist a moderate blow, and yet be translucent. A quantity of sheets 

 of mica were procured from Calcutta, which, when fixed into the cast-iron 

 window frames, were found to resist the blow of a chipping of iron driven oflf 

 by the chisel with such force as would have shivered a pane of glass. Mica 

 possesses both toughness and elasticity, and when a piece of iron does pene- 

 trate it, merely a hole is made large enough to allow the piece to pass, while 

 the other parts remain uninjured. It is not quite so transparent as glass, but 

 it is not so much less so as to be objectionable ; but this circumstance is not 

 important at Butterly, as, in consequence of the quantity of fluoric acid gas 

 evolved from the fluate of lime used as a flux in the blast furnaces, the glass 

 in the windows is speedily acted upon, and assumes the appearance of being 

 ground. Mica is a little more expensive than common glass ; but, as its 

 duration promises to be much longer, it must be more economical ; and if 

 an extensive use of it could be induced, a more ready supply would be ob- 

 tained — probably from Pennsylvania or from Russia, where it is commonly 

 used for windows in farm-houses, and also on board ships of war, as it is less 

 liable to be fractured Ij^v the concussion of the air during the discharge of 

 heavy artillery. It can be procured of almost any dimensions necessary for 

 ordinary purposes, as it has been found in Russia in masses of nearly 3 feet 

 diameter. It is susceptible of very minute subdivision, as, according to 

 llaiiy, it may be divided into plates no thicker than ^ „ „'^j „ „ of an inch. 



" On a specimen of White Cedar from Bathurst, Aew Brnnsirici, sent by 

 Mr. Cliurchill." 



The specimen exhibited to the meeting was of the <limensions calculated 

 for a railway sleeper, for which use it was proposed to introduce this timber, 

 as it is stated to possess, in a very superior degree, the quality of durability 

 in situations calciUated to try its properties. It can be imported at about 

 3s. 9(f. to 4s. per sleeper. 



Mr. Hawkins observed, that he knew that species of timber well, having 

 seen it extensively employed in the United States. It is an evergreen tree, 

 and grows only in wet or boggy grounds, and is found most plentifully in 

 New Jersey, Maryland, and Virginia. It attains the height of 70 to 80 feet, 

 but is rarely more than 3 feet in diameter. The concentric circles in it are 

 always perfectly distinct, and prove that the tree only arrives at its full 

 growth after a long term of years — as many as 277 anmdar rings have been 

 counted in a trunk 21 inches diameter, at 5 feet from the ground. The wood 

 is light, soft, fine grained, and easily wrought. It has an aromatic odour, 

 which it preserves as long as it is guarded from humidity. It resists alter- 

 nations of dryness and moisture better than any other wood, and on this 

 account is extensively used for shingles for roofing. They sell at Baltimore 

 for 4 or 5 dollars per 1000. These shingles will last from 30 to 40 years. 

 It is in great demand for household utensils, so much so that a distinct class 

 of coopers are called cedar coopers. It is used for boat building on account 

 of its great buoyancy. Cedar boards are sold at Philadelphia at 20 dollars 

 per 1000 feet. White cedar rails, with red cedar posts, form the most du- 

 rable kind of fence, being known to have lasted from 50 to 60 years. The 

 rails are sold at 6 to 8 dollars per 100, and the posts at 12 or 15 cents each. 



Mr. Brunei did not think it was a cheap or a strong wood. He had used 

 it chiefly for covering locomotive boilers, as it resisted heat better than any 

 other wood. AMien he purchased some there was but little in the market, 

 and it was consequently dear. 



Mr. Joseph Home oiijected to its use for sleepers on account of its ten- 

 dency to split 30 easily ; but he had found it resist wet perfectly. 



April 7. — The President in the Chair. 



The following were balloted for and elected :— Thomas Hawksley, as a 

 Member ; William Pole and John Dickenson, as Associates. 



