In blasting the Woodhead tunnel, in the county of Chester, not less than three thousand five hundred barrels of gunpowder, weighing about one hundred and sixty tons, were used in its formation. The average number of men employed was about a thousand; and during the six years the works were in progress, twenty-six men were killed. There were about 400 minor accidents, many of them attended with loss of limb, and the sum total of the casualties, in proportion to the men employed, was greater, according to Mr. Edwin Chadwick, than was suffered by the British army in the battles of Talavera, Salamanca, Vittoria, and Waterloo. ~Powder used on S. Eastern Railway.~ In the formation of the South-Eastern Railway, the blasts of the cliffs between Dover and Folkestone have astonished even scientific men. On one occasion 18,500 pounds of gunpowder were ignited by galvanic action at the same instant, which severed from the Round-down cliff, the height of which is 375 feet above the level of the sea, more than 1,000,000 tons of chalk. The fallen mass extended 1200 feet into the ocean, and covered a space of 18 acres. By another statement, the quantity of earth moved by the explosion was 400,000 cubic yards, and was a saving to the Company of £7,000. ~No. of men employed at Waltham Abbey.~ ~Quantity made.~ There are 134 men employed in the Government works at Waltham Abbey in the manufacture of gunpowder, who make about 9,000 barrels a year. The premises are near two miles long, consisting of detached mills, &c., on a small stream, which runs through the whole length of the premises and communicates with the Thames, whereby there is water-carriage to the Government Powder Magazines at Purfleet. The barges conveying powder are not allowed to anchor in the river off London during the night. Where two buildings are adjacent, there are frequently heavy buttresses of masonry between them, and lightning conductors are placed in great numbers. ~Saving to Government.~ There is a great saving, amounting to upwards of £300,000, in the cost of powder, when compared to the price paid to the merchants in seven years of the war from 1809 to 1815, from the Government having Waltham Abbey, Faversham, and Ballincollig. ~Improved Quality.~ At Waltham Abbey, in a very few years after it was constructed, the powder was so improved, that the charge of powder to the weight of shot was reduced from one-half to one-third; therefore two barrels were used instead of three--an advantage in stowing on board ship as well as in the field. ~Made by Contract.~