The Woodhead Tunnel, on the Manchester and Lincolnshire Railway, is upwards of three miles long. It was originally built for a single track, its dimensions being 14 feet wide at the head of the rails, and 18 feet 3 in. high from the rails to the under side of the arch; which are almost exactly the dimensions of the present section of the Hoosac Tunnel. After a few years of use, the increase of business required another track and so a second tunnel of exactly the same size was built parallel with the first. It is a double tunnel with a thick dividing wall between, pierced with twenty-one arched openings. Five of the original shafts have been kept open. The deepest of these is more than six hundred feet, and the least about three hundred. The rock through which the tunnel passes consists of millstone grit, a hard material, and shale, a kind of indurated clay. The Kilsby Tunnel is more than a mile and a quarter long, and is built in Roman or metallic cement, under a bed of quicksand, from which it took nine months to pump the water, through shafts on either side of the sand bed. During a considerable portion of that time, the water pumped out was two thousand gallons a minute. The quicksand extended over 1350 feet of the length of the tunnel. The Watford Tunnel is a mile and one tenth long, excavated entirely from chalk and loose gravel, the treacherous nature of which rendered it a work of great difficulty, streams of gravel and sand sometimes pouring through the fissures of chalk, like water. The Netherton Tunnel is one mile and three quarters long. For its construction 17 shafts were sunk, their total depth being 3,083 feet, the least depth of any one being 63 feet, and the greatest, 344 feet. There were 36 faces to work at, and the progress at each face was 10 1-2 feet per month. The tunnel was completed in two years. From these brief descriptions of a few of the tunnels in England examined by Mr. Storrow, one can form a pretty correct opinion of the ordinary difficulties in tunneling which have been met and overcome by the English engineers. Mr. Storrow says that tunnels are not considered there such formidable works as they have generally been esteemed in our Northern States. They are so common that they have long ceased to attract the attention of travelers, more than eighty miles in aggregate length being already in use. Mr. Storrow estimates the average progress made in the construction of the English tunnels at about thirty feet per month on one face, and that the cost per yard varies from $125 to $250, for ordinary tunnels; but where peculiar difficulties were met, the cost has reached to from $500 to $750 per yard.