Which Reasons Support Which Point

Canals and Railways

Between 1760 and 1830 Britain built about four thousand miles of canal. Within forty years of that, most of it was losing money. A canal boat carried thirty tons behind one horse, where a cart carried two. That was transformative for coal and stone, which are heavy, cheap and not in a hurry. But a canal cannot climb without locks, cannot be built where there is no water, and freezes. A boat averaged three miles an hour. The railways did not beat canals on cost per ton at first. They beat them on speed, on reliability, and on where they could go — a railway can cross a watershed a canal cannot. Many canal companies were bought by railway companies, sometimes specifically in order to close them. By 1900 most of the network carried nothing. Some of it is now used more than it ever was, by people on holiday.

Why the Thames Froze

Between 1309 and 1814 the Thames froze hard enough to walk on at least twenty-four times. Since 1814 it has not once. The usual explanation is that the climate has warmed. That is part of it, and not most of it. Old London Bridge had nineteen arches on wide stone piers. The piers took up so much of the channel that the bridge acted as a weir, slowing the water upstream almost to a standstill. Still water freezes; moving water does not. The river was also shallower and wider then, spreading over land that has since been embanked. Shallow water loses heat faster. Old London Bridge was demolished in 1831. The embankments were built between 1862 and 1874. The river that flows through London now is narrower, deeper and faster than the one that froze — and it would not freeze in a colder winter than any of those.