Despite these drawbacks, there is no reason to think that the appointment of postmaster was not eagerly sought for, or that when obtained there was any general disposition to throw it up. The explanation is obvious. In the first place the appointment carried with it the exclusive right of letting post-horses. This monopoly, at all events on the more frequented roads, must have been remunerative; and it must have been especially remunerative where, as appears to have been generally the case, the postmaster was also innkeeper. Travellers were drawn to his house, for it was only there that they could procure horses to pursue their journey. He was, in a word, assured of custom. Other sources of emolument were--1st, gratuities, varying according to distance, from 1d. to 3d., on every letter he collected or delivered; and 2nd, what were technically called "Bye-letters." This term, whatever may have been the case a century before, had now a distinctive meaning. It meant letters which stopped short of London,[13] letters upon which at that time there was no check. In 1690 the postage on these letters was probably not large; but, large or small, the whole or all but the whole of it found its way into the pockets of the postmasters, and it was one of the first cares of the new postmasters-general to consider how the diversion might be stopped. [13] In the agreement with Ralph Allen, dated thirty years later, bye-letters are defined to be "letters not going or coming from, to, or through London." Such, in England, was the condition of the Post Office when Cotton and Frankland assumed the direction of it in the month of March 1690. In Scotland the posts were under separate direction, the direction of the Secretary of State for that part of the kingdom, and subject to the control of the Scotch Parliament. For purposes of convenience, however, an arrangement had been made between the two Post Offices. On letters between London and Edinburgh in both directions the English Post Office took not only its own share of the postage but the whole; and, in return, it paid the salaries of all the postmasters and defrayed the cost of all expresses between the Border town of Berwick-on-Tweed and Edinburgh. The correspondence at this time passing between the two capitals was of the slightest. It is true that for the three years ending March 1693 the amount due to the London office for postage on letters to Edinburgh was £1500, or at the rate of £500 a year; but the correspondence of the Secretary of State for Scotland, or "Black-box" as it was called, from the colour of the box in which it was carried, would probably account for nearly the whole. In 1707, which no doubt was a busy year in consequence of the Act of Union, the cost of carrying this box to and fro averaged £66 a month.