292

HISTORY OF ENGINEERING.

Book I.

separated by clean and well defined joints, like the secondary on which they rest; thesebasins are of less extent, and derive their form from the rectifying of the beds, the elementsof which they are constituted being the same as those found on the neighbouring hills ;the several beds are arranged in a regular manner, and their separation is formed by a laverof sand, through which the water freely percolates; in these several sandy fissures it acquiresforce as it descends, and at great depths, its pressure being augmented, the flow is renderedconstant.

These soils are undoubtedly the best for sinking Artesian wells, because they have attheir base courses of sand lying on impermeable clays, and are less subject to dislocation orrupture than rocks of the older formation. Such strata are easily examined, and areusually found rising from the centre of the basin, and following an inverse direction to thatof the inclination of the water, which like a subterranean river pursues a downwardcourse till it meets with an outlet. They frequently become broken when the water theycontain weeps into small rivulets, and is carried away on the surface.

Where the well has been bored at Grenelle, the upper stratum or tertiary deposit is 41metres in thickness ; the next is composed of chalk mixed with flint, 99 metres ; then agrey chalk, without any silex, 25 metres ; to this succeeded a grey chalk, in which wereiron pyrites, 341 metres ; then a wealden clay, grey sand, and a sandy clay, in which werefound ammonites and other fossils ; the whole depth bored through being 548 metres, orabout 1798 feet.

The work was commenced on the 30th of November, 1833, by M. Mulot, and water wasobtained in February, 1844, at an expense of 303,000 francs.

The. railroads of France , Belgium , and Germany are progressing, and will probably becomethe only communications between the various towns and cities of the continent ; and in afew years the diligence and post carriage will only be remembered as ancient modes ofconveyance. The railroads already laid down in Belgium and Prussia are worked in anadmirable manner, and at far less cost than those of England ; the engineering difficultiesovercome beyond Liege , on the way to Cologne , the cutting and tunnelling and completingthe lines, rival any that have been hitherto executed. The greater part has been done bythe government: as most of the rails, carriages, and machinery employed upon these under-takings were first sent from England, no particular description of them is required ; andalthough the several foreign governments have established manufactories of their own, mostof them are provided with models and workmen from this country.

When the whole of the lines projected are completed, it will be a highly interesting taskfor the engineer to draw up an account of their difficulties and cost, and compare them withwhat has been performed during the same period of time at home.

Of the continental railways completed, first may be cited those in France : that of St. Ger-mains, 1miles in length ; Versailles , the right bank, 14 miles; the left bank 10J miles ;the Strasbourg , which is open from the Rhine to Switzerland , 87 miles; Paris andOrleans, 82 miles; Paris and Rouen , 84 miles; Rouen and Havre, 57 miles; Montpel­ lier and Cette, I6| miles; Mulhausen and Tham, 11^ miles; St. Stevens and Lyons, 31miles and many others are in progress.

Of the Belgian railroads complete, there is the north line, from Brussels to Antwerp ,27j miles ; west line , Malines to Ostend , 76j miles ; east line, Malines to the Prussianfrontier, 82^ miles ; south line, Brussels to the French frontier, 51 miles ; Client to theFrench frontier and Tournay, 48 miles; and Braine la Compte to Namur , 41 miles.

The whole 326j miles cost about 4,114,354/., or 12,611/. per mile.

Among the German lines opened may be mentioned the Leipzig and Dresden , in length7l£ miles ; Leipzig and Magdeburg , 72 miles; Berlin and Potsdam, 18 miles ; Berlin andStettin , 89 miles; Berlin and Frankfort on the Oder, 48 miles; Altona and Kiel, 63 miles;Brunswick and Osehersleben, 30 miles ; Brunswick and Hanover, 40 miles; Cologne andAix-la-Chapelle , 54 miles ; Cologne and Bonn , 20 miles ; Dusseldorf and Elberfeld, 17miles; Frankfort and Wiesbaden , 26 miles ; Manheim, Carlsruhe, and Kiel, 70 miles ;Nuremberg and Furth , 5 miles ; Vienna and Gloggnitz , 53 miles ; Breslau and Friburg ,40 miles; Budweis and Gemunden , 120 miles; and several others of great extent, nearlyready to be opened, and in progress.