nconstant: it was costly, too, because
at any time the labourers might be obliged to sit at the pit's mouth for
weeks together, whistling for a gale or waiting for the water to be got
under again. But steam had already been used for pumping upon one or two
estates in England--rather as a toy than in earnest--before the middle
of the seventeenth century, and the attempt to employ it was so obvious
as to be practically unavoidable.[3] The water trickling into the coal
measures[4] acted, therefore, like water trickling upon chemicals that
have long been mixed together dry and inert. Immediately the latent
reactions were set going. Savery, Newcomen, a host of other workers,
culminating in Watt, working always by steps that were at least so
nearly obvious as to give rise again and again to simultaneous
discoveries, changed this toy of steam into a real, a commercial thing,
developed a trade in pumping engines, created foundries and a new art of
engineering, and almost unconscious of what they were doing, made the
steam locomotive a well-nigh unavoidable consequence. At last, after a
century of improvement on pumping engines, there remained nothing but
the very obvious stage of getting the engine that had been developed on
wheels and out upon the ways of the world.

Ever and again during the eighteenth century an engine would be put upon
the roads and pronounced a failure--one monstrous Palaeoferric creature
was visible on a French high road as early as 1769--but by the dawn of
the nineteenth century the problem had very nearly got itself solved. By
1804 Trevithick had a steam locomotive indisputably in motion and almost
financially possible, and from his hands it puffed its way, slowly at
first, and then, under Stephenson, faster and faster, to a transitory
empire over the earth. It was a steam locomotive--but for all that it
was primarily _a steam engine for pumping_ adapted to a new end; it was
a steam engine whose ancestral stage had developed under conditions that
were by no means exacting in the matter of weight. And from that fact
followed a consequence that has hampered railway travel and transport
very greatly, and that is tolerated nowadays only through a belief in
its practical necessity. The steam locomotive was all too huge and heavy
for the high road--it had to be put upon rails. And so clearly linked
are steam engines and railways in our minds that, in common language
now, the latter implies the former. But inde