Titus Livius (Livy), The History of Rome, Book 24
Frank Gardener Moore, Professor Emeritus in Columbia University, Ed.

34. And an undertaking begun with so vigorous an assault would have met with success if one man had not been at Syracuse at that time. [2] It was Archimedes, an unrivalled observer of the heavens and the stars, more remarkable, however, as inventor and contriver of artillery and engines of war, by which with the least pains he frustrated whatever the enemy undertook with vast efforts.¹ [3] The walls, carried along uneven hills, mainly high positions and difficult to approach, but some of them low and accessible from level ground, we reequipped by him with every kind of artillery, as seemed suited to each place. [4] The wall of Achradina, which, as has been said already, is washed by the sea, was attacked by Marcellus with sixty five-bankers.² [5] From most³ of the ships archers and slingers, also light-armed troops, whose weapon is difficult for the inexpert to return,⁴ allowed hardly anyone to stand on the wall without being wounded; and these men kept their ships at a distance from the wall, since range is needed for missile weapons. [6] [p. 285]Other five-bankers, paired together, with the inner⁵ oars removed, so that side was brought close to side, were propelled by the outer banks of oars like a single ship, [7??] and carried towers of several stories and in addition engines for battering walls. To meet this naval equipment Archimedes disposed artillery of different sizes on the walls. [8] Against ships at a distance he kept discharging stones of great weight; nearer vessels he would attack with lighter and all the more numerous missile weapons. [9] Finally, that his own men might discharge their bolts at the enemy without exposure to wounds, he opened the wall from bottom to top with numerous loopholes about a cubit wide,⁶ and through these some, without being seen, shot at the enemy with arrows, others from small scorpions. [10] As for the ships which came closer, in order to be inside the range of his artillery, against these an iron grapnel, fastened to a stout chain, would be thrown on to the bow by means of a swing-beam projecting over the wall. When this⁷ sprung backward to the ground owing to the shifting of a heavy leaden weight, it would set the ship on its stern, bow in air. [11] Then, suddenly released, it would dash the ship, falling, as it were, from the wall, into the sea, to the great alarm of the sailors, and with the result that, even if she fell upright, she would take considerable water. [12] Thus the assault from the sea was baffled, and all hope shifted to a plan to attack from the land with all their forces. [13] But that [p. 287]side also had been provided with the same complete⁸ equipment of artillery, at the expense and the pains of Hiero during many years, by the unrivalled art of Archimedes. [14] The nature of the place⁹ also helped, in that the rock on which the foundations of the wall were laid is generally so steep that not only missiles from a machine, but also whatever rolled down of its own weight fell heavily upon the enemy. [15] The same circumstance made approach to the wall difficult and footing unsteady. [16] So, after a war council, since every attempt was being balked, it was decided to give up the assault and merely by a blockade to cut off the enemy by land and sea from their supplies.