On 19th February 1891, the Blackpool Tower Company Limited was registered. The company purchased the land and laid out foundations. The Tower is built on a foundation of cotton bales, to ensure flexibility in high winds, and to ensure that in the unlikely event, Heaven forbid, that the Tower should topple, then it would land safely in the chilly waters of the Irish Sea. On 29th September 1891, the foundation stone was laid, at a ceremony attended by luminaries from the borough and from numerous other northern towns.
Thats from here:
http://www.wardsbookofdays.com/14may.htm