have posted anything about the horses lately, then it is time to change this pattern - :) , so from the XVIII century horse literature classic comes this definition of a bit:
The title - 'The Farriers's and Horseman's Complete Dictionary: Containing the Art of Farriery in All Its Branches; with Whatever Relates to the Manage, and to the Knowledge, Breeding, Feeding, and Dieting of Horse' by James Williams et al , 1759.
*''BIT, or Bitt, or Horse-bitt, in general, signifies the whole machine of all the iron appurtenances of a bridle, as the bit-mouth, the branches, the curb, the sevil-holes, the tranchefil, and the cross chains: but oftentimes it signifies only the bitmouth in particular.
The fourth sort is called the cannon-mouth with the liberty after the form of a pigeon's neck. When a horse's month is too large, so that the thickness thereof supports the mouth of the bit, this it cannot work its usual effects upon the bars; this liberty will a little disengage it, and suffer the mouth of the bit to come at and rest upon his gums, which will make him so much the lighter upon the hand.
The port-mouth is a cannon with an upset or mounting liberty proper for a horse with a good mouth, but a large tongue; having its effects upon the lips and gums; and because the tongue is disengaged, it will subject the horse that hath high bars, and in some degree sensible.
* oroginal spelling