ENGINEER, INVENTOR

Work
Diades was an engineer who accompanied Alexander the Great on his expedition. A pupil of Polyides of Thessaly, he invented many siege engines for his patron and is cited by Athenaeus and Vitruvius. These include:

- Movable towers: Siege engines carried in sections and assembled before the walls.

- Battering ram: Siege engine designed to breach a wall, similar in construction to the "tortoise". Like the catapults and ballistae, it had a central groove within an upright frame; this was 23.10 metres long and 0.46 metres tall, and supported a cross-wise winch. A pair of pulleys on either side of the front end operated the battering ram, which was fitted with an iron head. Small cylinders lining the groove made it easy to speed up or slow down the action of the ram.

- Scaling engine: A device to enable besiegers to scale walls more easily.

- Battering crane: A kind of wrecking ball.

- Wheel-mounted battering ram: A description of this construction still survives. It was at least 27.72 metres tall and 7.85 metres wide, and tapered, so that the top was one fifth the sectional dimension of the base. The supporting beams in the base were 23 x 23 cm, and the swivel beam 15 cm. The tower was ten storeys high and each level had window-type openings. These siege towers were covered with untanned hides to protect them and the soldiers inside.

- Tortoise- ram: A construction 7.39 m tall and 14.78 m wide, with a small three-storey tower on top. The upper levels were equipped with slings and catapults, while the lower carried a store of water in case the construction caught fire. The battering ram was housed inside the "tortoise". It was slung from a drum, which facilitated the back-and-forth movement of the ram.

- Boarding platform: A kind of portable bridge for boarding enemy ships during naval engagements. It is described by Vito and cited by Athenaeus the Peripatetic. Given the similarity of their descriptions, Cicorius thinks that both authors drew on the writings of Agesistratus.