The Roman History · Amm. 23.4.6

Then when a conflict begins, a round stone is placed on the sling, and four youths on each side, loosening the bar to which the cords are attached, bend the pin back till it points almost upright into the air; then the worker of the engine, standing by on high ground, frees by a blow with the heavy hammer the bolt which keeps down the whole engine; and the pin being set free by the stroke, and striking against the mass of cloth shreds, hurls forth the stone with such force as to crush whatever it strikes.

Ammianus Marcellinus · translated by C. D. Yonge · 1911 reprint
C. D. Yonge translation (preface dated February 1862); G. Bell and Sons, 1911; Project Gutenberg #28587
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