ISM.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



453 



appearance, suggesting the idea of considerable danger, even from 

 the fall of a very small mass of rock from the top of the cutting, 

 should it happen to alight upon a passing train. 



At Red Hill, which is about two miles south of the Merstham 

 tunnel, the South-Eastern Railway diverges from the Brighton line liv 

 a short curve, which forms an arc of a circle one mile in diameter. 

 The first work which attracts attention on the South-Eastern line is 

 the great tunnel through the green-sand formation at Bletchingley 

 3| miles from the junction with the Brighton line. This tunnel is 1326 

 yards in length, and is built in the form of an ellipsis with a circular in- 

 vert. The width of the tunnel in the widest part, namely, in the minor 

 axis of the ellipse is 24 feet, its width at the invert is 22 feet 3 in., 

 the versed sine of the invert is 3 feet, and the full vertical height of 

 the tunnel is 25 feet, measured from the hollow of the invert to the 

 crown of the arch. I take these dimensions from the report of 

 General Paslev on the opening of the railway. In the neighbourhood 

 of Bletchingley, and in the same range of sand hills as that of which 

 Red Hill forms a part, are the famous Fullers' earth quarries at Nut- 

 field. This mineral is extensively carried into the clothing districts 

 of Yorkshire and the west of England, and is of great importance in 

 the woollen manufacture. 



It is worthy of notice that the first public railway constructed in 

 the south of England, was that laid down from Wandsworth to 

 Merstham, for the purpose of conveying the lime, firestone, and ful- 

 ler's earth of Merstham, Gatton, and Nuffield, to Croydon and Wands- 

 worth, from which places these minerals were sent by barges up the 

 Thames and through the Croydon Canal. This ancient railway was 

 called the Surrey iron tramroad, and was the work of Mr. Jessop a 

 celebrated engineer, who designed it about the beginning of the pre- 

 sent century. The minerals formerly carried by this tramroad are 

 now conveyed by the Brighton Railway and by carts along the public 

 road. The old tramway has been bought up by the Brighton Railway 

 • company, and all the iron and stone blocks sold off. The fullers' earth 

 pits are highly interesting to geologists, and are well worth a visit 

 from any one who has an hour to spare at Red Hill. The peculiar 

 earth known by this name is a variety of clay possessing highly ab- 

 stergent properties, which renders it of great value in the process of 

 cleansing woollen cloths from grease and other impurities. Fullers' 

 earth contains 53 per cent of silex, a larger proportion than most 

 other clays, and is distinguished by a remarkable property of falling 

 to pieces and readily passing into the state of impalpable mud on the 

 addition of water. In consequence of this it is necessary to preserve 

 it with great care from the injurious effects of rain, and the carts 

 containing it are commonly covered with tarpaulin for this purpose. 

 Some of the embankments on the Brighton Railway were partly com- 

 posed of fullers' earth in a wet condition, and this material being soon 

 reduced to a fluid state run out from its place in the embankment, which 

 as a matter of course, gave way, and subsided to an aiarming extent. 

 The fullers' earth of Nuffield is of two kinds, the blue and yellow, 

 the latter being esteemed the best. The pits contain great quantities 

 of a semi-transparent massive spar, termed by mineralogists the 

 ponderous earth or sulphate of baryles, (from ftapos weight.) Besides 

 the Bletchingley tunnel there is another short tunnel SS yards in 

 length, just before coming to Tunbridge, and a succession of cuttings 

 and embankments, some of which are of considerable extent. There 

 are also several large viaducts over branches of the Medway in the 

 neighbourhood of Tunbridge. 



The strata between Bletchingley and Tunbridge belong to the 

 weald clay formation, but at Tunbridge several of the cuttings 

 present sections of the Forest series, thus proving the interesting 

 fact that these latter strata encroach more upon the weald at this 

 place than shown on Mr. Greenough's and other geological maps. 

 The true weald clay is almost uniform in its appearance, consisting 

 commonly of the blue or brown varieties, with occasionally a thin bed 

 of imperfectly aggregated shelly limestone, whereas the Forest strata 

 consist of numerous alternations of sand and sandstone, with beds of 

 clay extremely various iu thickness, separating the layers of rock 

 from each other. This appearance, which is presented by the cut- 

 tinge near Tunbridge cannot be mistaken for that of the weald clay, 

 and hence ample reason appears to exist for examining into the ac- 

 curacy of the geological maps of this district. The principal works 

 between Tunbridge and Ashford are a deep cutting at Postern be- 

 tween that place and Headcorn, with several viaducts over the Teise 

 and the Beult feeders of the Medway, and one over the Stour, which 

 flows by Canterbury and falls into the sea at the Reculver. These 

 viaducts are principally built of timber, by which, of course, their 

 cost has been considerably diminished, although, at the same time, it 

 must be borne in mind, that they will decay much more speedily, and 

 probably prove not cheaper in the end than structures of masonry. 



The stations on this line have also been designed with a strict view 



to economy. Those at Tunbridge and Ashford are of considerable 

 size, the others consist of small wooden buildings stuccoed on the 

 outside, lined on the inside with canvas, and painted or papered in a 

 handsome manner. At each station there is a booking office on each 

 side of the railway, and these offices are not opposite to each other, 

 that intended for the down train being nearest to Dover, and that for 

 the up trains nearest to London. 



The permanent way on this line is constructed in a peculiar manner. 

 The rails weigh about 71 lb. per lineal yard, and are fixed in chairs 

 which are supported by transverse sleepers of timber. The chief 

 peculiarity consists in the form of the sleepers, two of which are 

 made by sawing a square log of Baltic fir diagonally through the 

 middle, so that each sleeper is a triangle in section. These triangular 

 sleepers are laid with the edge or vertex downwards, and the chair is 

 bedded upon the flat upper surface. The advantages of this plan are 

 said to comprise superior facilities for packing the sleepers so as to 

 secure them from disturbance, at the same time that its economy is 

 said to be greater than any other that has been tried. Considerable 

 difficulty has been experienced in procuring ballast for the permanent 

 way. This was originally supplied by the sand cutting at Red Hill, 

 but the material used was" of far too fine a quality, and is blown away 

 in great quantities during windy weather. I hear that the company 

 is now about either partially, or entirely, to re-ballast the line with 

 gravel from Croydon, the expense of carriage by the railway being so 

 small that thev can afford to go all this distance for a superior material. 



I have already said that the railway commences by a curve when it 

 leaves the Brighton line, and with the exception of this curve the line 

 may be considered straight all the way to Ashford, a distance of 

 nearly forty-five miles from its junction with the Brighton Railway. 

 Throughout this long distance, with the exception of the small pro- 

 trusion of Forest strata at Tunbridge, the line lies entirely in the 

 weald clay, which forms a flat belt of country about seven miles wide, 

 risino- to the north towards the sand range which accompanies the 

 north Downs, and bounded on the south by the gradual slope of the 

 Forest district, which assumes in central Kent an elevation of GOO or 

 800 feet. The weald thus lies in a valley between the sand range on 

 the north and the Forest country on the south. It is everywhere 

 covered by abundance of fine oak timber, which flourishes in such 

 luxuriance upon the weald clay, that William Smith the geologist, 

 wdio first traced the succession of strata in this part of England, 

 adopted the name of the oak tree clay for this formation. 



Whoever has paid any attention to the physical geography of this 

 country must have been impressed by the important connection be- 

 tween the Wealden district and the surrounding barrier of chalk 

 which everywhere accompanies it. A series of cold wet clays, re- 

 markablv adhesive and retentive of moisture, composes the subsoil 

 of the Wealden country, a soil so mechanically constituted as to be 

 almost incapable of cultivation without the action of frost or of some 

 other acrent capable of producing a mechanical division and sepa- 

 ration of its adhesive particles. Just such an agent is quick lime, 

 which being mixed with the stiff heavy clay, bursts and splits the 

 clods into many pieces, and produces a soft mellow soil which is ca- 

 pable of being cultivated to great advantage. For many years it has 

 been the practice of the best farmers in the wealds both of Kent and 

 Sussex to transport large quantities of chalk either burnt in the state 

 of quick lime, or in the native state of chalk, to be burnt on their 

 own land, for the purpose of mixing with the soil. It is a well- 

 known fact that lime is even carried to some parts of the weald, 

 a distance of 20 miles or more over such execrable roads, that the 

 cost of carriage alone must exceed 1/. per ton. Now mark the cir- 

 cumstances of the great extent of wealden clay through wdnch the 

 South-Eastern Railway passes. On one part of the line, namely, ad- 

 joining the great cutting and tunnel at Merstham, there is a million 

 tons of chalk lying absolutely waste and useless, encumbering the land 

 by its presence, and forming unsightly heaps of spoil by the side of 

 the railway. Why is not this chalk burnt into lime and conveyed by 

 the railway into the clay districts, where it would produce such ob- 

 vious improvement? Chalk maybe bad in equal abundance from 

 the southern extremity of the line at the works beyond Folkstone, so 

 that the distance of carriage to no part of the clay district on the 

 direct line would exceed 25 miles, and the cost at the ordinary charge 

 for carrying lime would be about 8s. per ton for the whole distance. 

 If the railway were employed in this service it would prove of incal- 

 culable advantage to the agriculturists of Kent, as it runs directly 

 through the middle of the wealden district in its longest direction, and 

 the carriage by wagon from the sides of the railway would not exceed 

 four or five miles in the most unfavourable cases. I did not observe 

 a single ton of lime!) on the railway when I passed over it, and I 

 greatly fear that hitherto the agriculturists of this district have been 

 grossly negligent of the advantages within their reach. 



