Chapter Horse. to Horse-shoes of H by Brewer's Phrase & Fable

Horse-power A measure of force. Watt estimated the "force" of a London dray-horse, working eight hours a day, at 33,000 foot-pounds (q.v.) per minute. In calculating the horse-power of a steam-engine the following is the formula: -

    P × A × L × N /33,000 deduct 1/10 for friction.

   P, pressure (in lbs.) per sq. inch on the piston.
   A, area (in inches) of the piston.
   L, length (in feet) of the stroke.
   N, number of strokes per minute.

Horse Protestant As good a Protestant as Oliver Cromwell's horse. This expression arises in a comparison made by Cromwell respecting some person who had less discernment than his horse in the moot points of the Protestant controversy.

Horse-radish The pungent root.

Horse-shoes were at one time nailed up over doors as a protection against witches. Aubrey says, "Most houses at the West-end of London have a horse-shoe on the threshold." In Monmouth Street there were seventeen in 1813, and seven so late as 1855.

"Straws laid across my path retard;
The horse-shoes nailed, each threshold's guard." Gay: Fable xxiii. part 1.

   It is lucky to pick up a horse-shoe. This is from the notion that a horse-shoe was a protection against witches. For the same reason our superstitious forefathers loved to nail a horse-shoe on their house-door. Lord Nelson had one nailed to the mast of the ship Victory.
    There is a legend that the devil one day asked St. Dunstan, who was noted for his skill in shoeing horses, to shoe his "single hoof." Dunstan, knowing who his customer was, tied him tightly to the wall and proceeded with his job, but purposely put the devil to so much pain that he roared for mercy. Dunstan at last consented to release his captive on condition that he would never enter a place where he saw a horse-shoe displayed.