84 ADDRESS TO THE BRITISH ASSOCIATION, 1881. 



present time, with steel at his command, Mr. Fowler 

 is engaged in carrying out the design for a railway 

 bridge over the Forth, of two spans of 1,700 feet each ; 

 that is to say, of nearly one third of a mile in length. 

 In artillery, bronze has given place to wrought iron 

 and steel ; the 68 -pound shot, which was the heaviest 

 projectile fifty years ago, with its range of about 1,200 

 yards, is being replaced by a shot of nearly a quarter- 

 ton weight, with a range of nearly five miles ; and 

 the armour-plates of ships are daily obtaining new 

 developments. 



But it is in railroads, steamers, and the electric 

 telegraph that the progress of mechanical science has 

 most strikingly contributed to the welfare of man. 



As regards railways, the Stockton and Darlington 

 Railway was opened in 1825, but the Liverpool and 

 Manchester Railway, perhaps the first truly passenger 

 line, dates from 1830, while the present mileage of rail- 

 ways is over 200,000 miles, costing nearly 4,000,000,000^. 

 sterling. It was not until 1838 that the Sirius and 

 Great Western first steamed across the Atlantic. The 

 steamer, in fact, is an excellent epitome of the progress 

 of the half-century ; the paddle has been superseded by 

 the screw ; the compound has replaced the simple 

 engine ; wood has given place to iron, and iron in its 

 turn to steel. The saving in dead weight, by this 

 improvement alone, is from 10 to 16 per cent. The 

 speed has been increased from 9 knots to 15, or even 

 more. Lastly, the steam -pressure has been increased 

 from less than 5 Ibs. to 70 Ibs. per square inch, while 

 the consumption of coal has been brought down from 

 5 or 6 Ibs. per horse-power to less than 2. It is a 



