340 A Short History of The World ship to put to sea was also an American, the Phoenix, which went from New York (Hoboken) to Philadelphia. So, too, was the first ship using steam (she also had sails) to cross the Atlantic, the Savannah (1819). All these were paddle-wheel boats, and paddle- wheel boats are not adapted to work in heavy seas. The paddles smash too easily, and the boat is then disabled. The screw steam- ship followed rather slowly. Many difficulties had to be surmounted before the screw was a practicable thing. Not until the middle of the century did the tonnage of steamships upon the sea begin to overhaul that of sailing-ships. After that the evolution in sea transport was rapid. For the first time men began to cross the seas and oceans with some certainty as to the date of their arrival. The transatlantic crossing, which had been an uncertain adventure of several weeks— which might stretch to months — ^was accelerated, until in 1910 it was brought down, in the case of the fastest boats, to under five days, with a practically notifiable hour of arrival. Concurrently with the development of steam transport upon land and sea a new and striking addition to the facilities of human intercourse arose out of the investigations of Volta, Galvani, and Faraday into various electrical phenomena. The electric telegraph came into existence in 1835. The first underseas cable was laid in 1851 between France and England. In a few years the telegraph system had spread over the civilized world, and news which had hitherto travelled slowly from point to point became practically simultaneous throughout the earth. These things, the steam railway and the electric telegraph, were to the popular imagination of the middle nineteenth century the most striking and revolutionary of inventions, but they were only the most conspicuous and clumsy first-fruits of a far more extensive pro- cess. Technical knowledge and skill were developing with an extra- ordinary rapidity and to an extraordinary extent, measured by the progress of any previous age. Far less conspicuous at first in everyday life, but finally far more important was the extension of man's power over various structural materials. Before the middle of the eighteenth century iron was reduced from its ores by means of wood-charcoal, was handled in small pieces, and hammered and wrought into shape. It was material for a craftsman. Quality and treatment were enormously dependent upon the experi- ence and sagacity of the individual iron worker. The largest masses of iron that could be dealt with under those conditions amounted
