Short answers, pulled from the story.
Canal Mania was the period of intense canal building in England and Wales between the 1790s and 1810s, accompanied by a speculative investment frenzy centred in the early 1790s. Investors poured capital into canal companies after the success of early ventures like the Bridgewater Canal demonstrated that waterway construction could be highly profitable.
Three factors converged: the end of the expensive American War of Independence in 1783 freed up capital; a long run of good harvests raised disposable income; and the financial success of the Bridgewater Canal, which cut Manchester coal prices by 50%, attracted investors with little personal interest in the goods being shipped.
Only one canal was authorised in 1790, the Glamorganshire Canal. By 1793, Parliament approved twenty new canals in a single year, including the Grand Junction Canal, the Ellesmere and Chester Canal, the Barnsley Canal, and the Stratford-upon-Avon Canal, among others.
The Glamorganshire Canal Company was authorised to raise £90,000 in 1790. By 1793, the combined authorised capital for the twenty new canals approved that year had risen to £2,824,700.
No. While some canals from the period became profitable, others never paid a dividend, including the Herefordshire and Gloucestershire Canal. The Grand Western Canal was never even completed, representing a total loss for its investors.
The Bridgewater Canal, built by the Duke of Bridgewater to ship coal from Worsley to Manchester, demonstrated that canals could be highly profitable. The price of coal in Manchester fell by 50% shortly after it opened, making the financial case for canal investment compelling to outside investors.