What is "hook ladder"

Hook \Hook\ (h[oo^]k; 277), n. [OE. hok, AS. h[=o]c; cf. D. haak, G. hake, haken, OHG. h[=a]ko, h[=a]go, h[=a]ggo, Icel. haki, Sw. hake, Dan. hage. Cf. Arquebuse, Hagbut, Hake, Hatch a half door, Heckle.]

1. A piece of metal, or other hard material, formed or bent into a curve or at an angle, for catching, holding, or sustaining anything; as, a hook for catching fish; a hook for fastening a gate; a boat hook, etc.

2. That part of a hinge which is fixed to a post, and on which a door or gate hangs and turns.

3. An implement for cutting grass or grain; a sickle; an instrument for cutting or lopping; a billhook.

   Like slashing Bentley with his desperate hook.
   --Pope.

4. (Steam Engin.) See Eccentric, and V-hook.

5. A snare; a trap. [R.]
   --Shak.

6. A field sown two years in succession. [Prov. Eng.]

7. pl. The projecting points of the thigh bones of cattle; -- called also hook bones.

8. (Geog.) A spit or narrow cape of sand or gravel turned landward at the outer end; as, Sandy Hook in New Jersey.

9. (Sports) The curving motion of a ball, as in bowling or baseball, curving away from the hand which threw the ball; in golf, a curving motion in the direction of the golfer who struck the ball.

10. (Computers) A procedure within the encoding of a computer program which allows the user to modify the program so as to import data from or export data to other programs.

    By hook or by crook, one way or other; by any means, direct or indirect.
    --Milton. ``In hope her to attain by hook or crook.''
    --Spenser.

    Off the hook, freed from some obligation or difficulty; as, to get off the hook by getting someone else to do the job.

    Off the hooks, unhinged; disturbed; disordered. [Colloq.] ``In the evening, by water, to the Duke of Albemarle, whom I found mightly off the hooks that the ships are not gone out of the river.''
    --Pepys.

    On one's own hook, on one's own account or responsibility; by one's self. [Colloq. U.S.]
    --Bartlett.

    To go off the hooks, to die. [Colloq.]
    --Thackeray.

    Bid hook, a small boat hook.

    Chain hook. See under Chain.

    Deck hook, a horizontal knee or frame, in the bow of a ship, on which the forward part of the deck rests.

    Hook and eye, one of the small wire hooks and loops for fastening together the opposite edges of a garment, etc.

    Hook bill (Zo["o]l.), the strongly curved beak of a bird.

    Hook ladder, a ladder with hooks at the end by which it can be suspended, as from the top of a wall.

    Hook motion (Steam Engin.), a valve gear which is reversed by V hooks.

    Hook squid, any squid which has the arms furnished with hooks, instead of suckers, as in the genera Enoploteuthis and Onychteuthis.

    Hook wrench, a wrench or spanner, having a hook at the end, instead of a jaw, for turning a bolthead, nut, or coupling.

n. A ladder with hooks at the end by which it can be suspended, as from the top of a wall.

A hook ladder, also known as a pompier ladder (from the French pompier meaning firefighter) is a type of ladder that can be attached to a window sill or similar ledge by the use of a hooked extending bill with serrations on the underside. The hooked ladder then hangs suspended vertically down the face of the building.

The ladder was developed to access buildings via enclosed alleys, lightwells and yards to which other types of ladder could not be taken. A pair of men and two ladders could be used to scale a building to considerable heights, by climbing from floor to floor and taking the ladders up behind and pitching to the next floor. The original French design was a single beam ladder with pairs of rungs projected outward on both sides of the beam. The British version was a conventional 2 string ash ladder around 13 foot (4m) long and around 10 inches (250mm wide). Hook ladders can be used to scale from floor to floor on multi-storey buildings by way of exterior windows. The ladders hook onto the window ledge by a "gooseneck" projecting from the top. Lengths vary from 10 to 16 feet.