11. It would be tedious, and indeed impossible, to detail the various works which a railway engineer has to superintend in the construction of the line, in the laying down of the rails or “permanent way,” and in the subsequent, or rather simultaneous, erection of the various station-houses, storehouses, workshops, &c. &c., the interior of which we shall soon have occasion to enter. An idea, however, of the magnitude of his operations may be faintly imparted by the following brief abstract of a series of calculations made by Mr. Lecount, one of the engineers employed in the construction of the southern division of the present London and North-Western Railway, and the writer of the article ‘_Railways_’ in the ‘Encyclopædia Britannica.’ The great Pyramid of Egypt was, according to Diodorus Siculus, constructed by three hundred thousand--according to Herodotus by one hundred thousand--men; it required for its execution twenty years, and the labour expended on it has been estimated as equivalent to lifting 15,733,000,000 of cubic feet of stone one foot high. Now, if in the same manner the labour expended in constructing the Southern Division only of the present London and North-Western Railway be reduced to one common denomination, the result is 25,000,000,000 cubic feet of similar material lifted to the same height; being 9,267,000,000 of cubic feet _more_ than was lifted for the pyramid; and yet the English work was performed by about 20,000 men only, in less than five years. Again, it has been calculated by Mr. Lecount that the quantity of earth moved in the single division (112½ miles in length) of the railway in question would be sufficient to make a foot-path a foot high and a yard broad round the whole circumference of the earth! the _cost_ of this division of the railway in penny-pieces being sufficient to form a copper kerb or edge to it. Supposing therefore the same proportionate quantity of earth to be moved in the 7150 miles of railway sanctioned by Parliament at the commencement of 1848 (_Vide_ Parliamentary Returns), our engineers within about fifteen years would, in the construction of our railways alone, have removed earth sufficient to girdle the globe with a road one foot high and one hundred and ninety-one feet broad! Abandoning, however, speculations of this nature, we will conclude our slight sketch of the principal works required for a railway by a few data, exemplifying the magnitude of the Britannia Bridge over the Menai Straits, the construction of which has been intrusted by its well-known inventor to the very able and experienced management of Mr. Frank Forster. The dimensions of this straight wrought-iron aërial gallery, through which passengers and goods are to travel by rail, are-- Total length of bridge, divided into 4 openings-- } 2 of 230 feet } } Feet. In. 2 of 460 feet } each } 1834 9