The Thames embankment, which was first proposed by Sir Christopher Wren, the architect of St. Paul's Cathedral, is now almost completed. This magnificent roadway, one of the finest in Europe, and which gives the modern observer some conception of what the Appian Way or Via Sacra were in the palmy day of ancient Rome, is fifty feet broad, and three and a half feet above the highest high-water mark. The embankment, which is constructed of Portland stone, and extends on the Surrey side from Westminster to Vauxhall bridge, a distance of nearly a mile, and on the Middlesex shore from Westminster to Blackfriar's bridge, a distance of fully a mile. The embankment is lined on both sides with trees which throw a pleasant shade under the summer sun, and serve to protect the thousands of people of both sexes, who seek in the evening a breath of fresh air always grateful to the tired and sweltering citizen. At different points, on both sides of the river, the embankment has magnificent stone terraces with stone stairs to enable wayfarers, who seek transportation up and down the river, to get on and off the numerous ferry boats that swarm and ply all over the Thames from Richmond to Rotherhithe. A description of the Thames tunnel, now closed to the public, may appropriately be included in this chapter. It was commenced by a joint stock company in 1824, after designs by Sir Isambard Brunel. Early in December, 1825, the first horizontal shaft was sunk. The difficulties encountered in the construction of the great engineering work can scarcely be overestimated. For a distance of five hundred and forty-four feet all went well, but at this point the river burst into the shaft, while the workmen were at labor, filling the excavation entirely in fifteen minutes, but fortunately no lives were lost. With great difficulty the water was pumped out and work resumed. After adding fifty-two feet to the original length of the shaft, the turbid Thames again broke through. Six men by this accident were smothered in the rush of angry waters, the remaining laborers escaping. Thrice again the river broke into the succeeding excavations, and at length the tunnel was completed to the Wapping side of the river. Here a shaft was sunk from the surface to meet it. In sinking this shaft, three distinct lines of piles, showing the existence of wharves below the present level of the Thames, were discovered.