Ballista balls, Burnswark, Hoddam and Shancastle, Glencairn

Ballistas were mobile horizontal wooden frames containing a central band of twisted ropes through which a wooden arm with a sling attachment was inserted. The wooden arm was pulled back against the force of the twisted ropes and when it was released it struck a verical wooden frame hurling the contents of the sling at the enemy. Burnswark was possibly a Roman military training camp and the ballista balls from there were probably used in practice sieges. The South Camp has three large mounds which are thought to be platforms for mounting ballistae.   Grierson collection    Accurately dressed sandstone artillery ball in Dumfries Museum, from the slope below Shan Castle Iron Age Hillfort. Weighs 2.25 Roman librae (0.74kg), diameter 8cm. This is similar in size and finish to several of the sandstone balls from Burnswark and is suitable for a librae ballista, the smallest stone-thrower in Vitruvius' list. It does not sit comfortably in the hand and is unlikely to have been intended for throwing either by hand or by means of a fustibalus (arm-extending stick with a sling). The smaller stones of about 0.17 amd 0.34 kg from Burnswark were most likely thrown by hand, or with the arm extension afforded by the fustibalus.   PREHISTORIC ANTIQUITIES Stone Implements, &c                                   40. Ball of greenstone, 3 1/8 inches in diameter, rough surface. Found in Glencairn 41. Ball of greenstone, 3 1/2 inches in diameter, rough surface. Found on Birrenswark Hill, Annandale 42. Ball of greenstone, 2 1/8 inches in diameter, with rough surface. Found in Lochar Moss   [extract] 748. Stone ball found at Burnswark in Annandale. Presented by Mr George Johnston. Forester at Castlemilk, Augt 1869. WILKINS, Alan "Roman Artillery". Shire Publications Limited, Princes Risborough, 2003 [see figure 51]