ever, decrease by any regular progression, neither are the curves employed in the arches of one kind, fourteen of them being in the Gothic or pointed style the rest are semi-cir- ;

cular, a variation adopted by the architect, Manuel dal Maga, from an apprehension, that

making the five principal arches semi-circular, he would considerably add to the expense. In the rest of the edifice, much judgment has been displayed no part of it has failed, or ;

appears to have received the least injury. This aqueduct was finished in 1738. The great earthquake, which in 1755, destroyed thousands of lives, in Lisbon, numerous houses, palaces, and churches, and shook all the peninsula, had no effect upon this noble structure, which continued to pour its waters into the ruined city, with the same equal flow, after, as before that great catastrophe. Over the arches there runs a vaulted corridor, 9 inches high, by 5 feet broad feet 6

internally. A continued passage runs through the centre of it, for the people who constantly attend to keep it in order, and a semi-circular channel or conduit of 13 inches diameter at each through which the water is conveyed. It is worthy of remark, that side, these channels are laid not in an inclined direction, as in other aqueducts, but horizontally to compensate for this, a small depression is made, at certain intervals, by which the ;

water is impelled along the horizontal line a manner, supposed by the natives, to require ,