HORNING, LETTERS OF, a term in Scots law. For merly all decrees of court for payment of money might be put in execution by letters issuing from the King's signet. These signet letters were called letters of horning or letters of four forms. Under them the debtor was charged four times succes sively to make payment, but in the fourth charge he was called on either to pay or to enter himself in a specified prison. Failing implement of the fourth charge he was denounced rebel at the horn. The method of declaring a person a rebel was by giving three blasts on a horn and publicly proclaiming the fact ; hence the expression "put to the horn." This system of execution was simplified by an act of 1837 (Personal Diligence Act), and execu tion is now usually by diligence. (See EXECUTION.)