By 1845 a full railway mania was raging. By the summer new schemes were being floated at the rate of more than a dozen a week. Scrip was sold by alley men, and the stock exchange resembled a country fair... Schemes for direct lines connecting little-known towns to other little-known towns became a craze, launched more with an eye to garnering investment than actual profits... "We see nine or ten proposals for nearly the same line, all at a premium, when it is well known that only one CAN succeed," said The Economist.
Trouble began in October 1845, when scrip ceased to pay a premium and shares in established railways began to fall.
W. Brian Arthur comparing the first dot com collapse to the railway mania of the 19th century, in a paper I fact checked for the March 2002 edition of Business 2.0. At one point in 1845, some 30 different railway investment publications were in circulation. Sound familiar?