Sling
2 of the 7 encyclopedias on this shelf carry an entry for Sling. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a well known device for casting stones or other missiles. It consists essentially of a broad bit or palm of leather and two stout thongs or strings, possibly a yard in length, one at each end. The slinger wraps the longer string about his hand for security and holds the other string between the thumb and forefinger. A pebble, leaden bullet, or other similar projectile is then placed in the loop at the middle of the sling. Sometimes a small hole in the leather is made to seat the pebble the more firmly. By whirling the sling over the head and releasing the short string at the proper moment, the missile may be hurled with prodigious force. Slings are of no little antiquity. In I Samuel we read that David prepared for combat with the Philistine giant Goliath by choosing five smooth stones from a brook. When the huge champion advanced, "David put his hand in his bag, and took thence a stone, and slang it, and smote the Philistine in his forehead, that the stone sunk into his forehead; and he fell upon his face to the earth." I Samuel xvii: 49. In the time of the Judges there were 700 men of Benjamin able to "sling stones at a hair-breadth and not miss." The Carthaginians and Romans enlisted formidable slingers from the Balearic Isles. The Saxons of the eighth century were expert slingers.
The Encyclopedia of Founding (1892)
A foundry device for handling and conveying flasks and loam-moulds. The stirrup-sling reaches from bottom lugs of a foundation-plate to the binders, or cross for binding the mould together, and serves the purpose of lifting the moulds also. Beam-slings are also stirrup, except that the lower end is usually made to fit the trunnion of a flask; by this means copes are reversed by simply lifting with one sling at each end of the beam. Chain-slings have stirrups, and are joined in pairs generally to one ring. The link-sling is simply a long welded link, and may be round, oval, or square ended. Rope-slings, being flexible, are extremely useful in the foundry. See BEAM-SLINGS; ROPE-SLINGS.