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In these excavations he suspended brazen vessels. Inone of them, near the place where the enemy was forminghis mine, the brazen vessels began to ring, from theblows of the mining tools which were working. Fromthis he found the direction in which they were endea-vouring to penetrate, and then prepared vessels of boilingwater and pitch, human dung, and heated sand, for thepurpose of pouring on their heads. In the night hebored a great many holes, through which he suddenlypoured the mixture, and destroyed those of the enemytliat were engaged in this operation. Similarly whenMarseilles was besieged, and the enemy had made morethan thirty mines ; the Marseillois suspecting it, loweredthe depth of the ditch which encompassed the wall, so-that the apertures of all the mines were discovered. Inthose places, however, where there is not a ditch, theyexcavate a large space within the walls, of great lengthand breadth, opposite to the direction of the mine, whichthey fill with water from wells and from the sea; so thatwhen the mouths of the mine open to the city, the waterrushes in with great violence, and throws down thestruts, overwhelming all those within it with the quantityof water introduced, and the falling in of the mine.When a rampart composed of the trunks of trees israised opposite to a wall, it may be consumed by dis-charging red hot iron bars against it from the balistse.When, also, a tortoise is brought up to batter a wall witha ram, a rope with a noose in it may be lowered to layhold of the ram, which being then raised by means of awheel and axle above, keeps the head suspended, so thatit cannot be worked against the wall: lastly, with burn-ing arrows, and with discharges from the balistse, thewhole machine may be destroyed. Thus all these citiesare saved and preserve their freedom, not by machines,but by expedients which are suggested through theready ingenuity of their architects. I have, in this book,