As for Scotland, he declared that "The roads in Scotland are worse than those in England, although materials are more {105}abundant, of better quality, and labour at least as cheap, and the toll duties are nearly double; this is because road-making, that is the surface, is even worse understood in Scotland than in England." He mentions that the Postmaster-General had been obliged to give up the mail-coach from Glasgow to Ayr on account partly of the bad roads and partly of the expense, there being ten turnpike gates in 34 miles of road. The roads were, in fact, McAdam continued, "universally in want of repair." Ample funds were already provided; but the surveyors employed by the turnpike trusts were "mostly persons ignorant of the nature of the duties they are called on to discharge,"[17] and the money brought in by a continual and apparently unlimited increase of the tolls was "misapplied in almost every part of the Kingdom." In some new roads made in Scotland the thickness of the materials used exceeded three feet;[18] but, said McAdam, "the road is as open as a sieve to receive water"; and what this meant he was able to show by pointing to the results of weather conditions on bad roads in the month of January, 1820. A severe frost was succeeded by a sudden thaw, accompanied by the melting of much snow, and the roads of the kingdom broke up in an alarming manner, causing great loss, much delay of the mails, and endless inconvenience. The cause of the trouble was explained by McAdam thus:-- "Previous to the severe frost the roads were filled with water which had penetrated through the ill-prepared and unskilfully-laid material; this caused immediate expansion of the whole mass during the frost, and, upon a sudden thaw, the roads became quite loose, and the wheels of the carriages penetrated to the original soil, which was also saturated with water, from the open state of the road. By this means many roads became altogether impassable." On the 1000 miles of road to which his own system had {106}been applied there had, he further said, been no breaking up at all by reason of frost. The figure here given suggests the extensive adoption of McAdam's system which was then proceeding. It was not only that old roads were being repaired according to his plan, but there was much construction of "macadamised" roads, the deficiencies of the existing roads having discouraged and checked the provision of new ones. Between 1818 and 1829, as told by Porter, in his "Progress of the Nation," the length of turnpike roads in England and Wales was increased by more than 1000 miles. In proportion, also, as the turnpike roads increased alike in number and in quality, through the wider adoption of McAdam's system, there was a corresponding impetus given to coaching in respect both to number of vehicles and to increase of speed, leading up to those "palmy days" of coaching which were only to close with the spread of the railway.