Some of the earliest work on the use of microwaves to transmit signals was carried out by the Indian physicist J. C. Bose. At Calcutta Town Hall, he demonstrated that the waves could propagate both through walls and the body of the governor, and used microwaves to activate relays that triggered a bell and fired a cannon ball. In 1897, Bose demonstrated the waves before the Royal Society in London. Amongst the apparatus he developed was a polariser that was constructed from a thick volume of Bradshaw’s Railway Timetable with sheets of tinfoil placed between the pages.