The window-tax goes back to 1695, but many of these windows are of later date than that. The tax did not become oppressive until after 1784. In that year the tax on a house of ten windows was raised from 11_s._ 4_d._ to £1. 4_s._ 4_d._, to £1. 12_s._ 0_d._ in 1802, and to £2. 16_s._ 0_d._ in 1808. On a house of twenty windows it was raised from £1. 14_s._ 8_d._ to £4. 9_s._ 8_d._ in 1784, to £7. 10_s._ 0_d._ in 1802, and to £11. 4_s._ 6_d._ in 1808. And on a house of thirty windows from £3. 3_s._ 0_d._ to £7. 13_s._ 0_d._ in 1784, to £13. 0_s._ 0_d._ in 1802, and to £19. 12_s._ 6_d._ in 1808. It thus became worth while to block up windows; and this, I believe, was the period when most of these windows were blocked up. Window-tax had been imposed in place of hearth-money, the notion being that the number of the windows would indicate the value of the house. But it played havoc with the health of the community, as people were willing to live and sleep in rooms with neither light nor air, in order to escape the tax. The same thing happened with ships. Dues were levied on tonnage; and formerly the tonnage of a ship was calculated from her length and breadth, the depth being reckoned as half the breadth, which was about the usual ratio when the rule was made. If the depth was more than half the breadth, the ship carried more cargo without any increase in the tonnage or the dues. And the result was that ships were built deeper and deeper, until the depth came to be about three-quarters of the breadth, and they became unsafe and foundered. Then came the Act of 1854, which put tonnage on the basis of a ton for every hundred cubic feet of space inside the ship, excepting space required for engines, crew, coal, etc. But space was reckoned in a way that led to unforeseen results. If a screw-steamer of 3000 tons had an engine-space of 380 tons, or 38,000 cubic feet, she was allowed a further 285 tons as coal-space; but, if her engine-space was brought up to 400 tons, the allowance was 560 tons. And in powerful tugs the deductions often came to more than the total from which they were to be deducted. Their nett tonnage being registered as 0, these vessels had no dues to pay.