Dean Swift is the great classic figure on the Holyhead Road at this period; although, to be sure, a very elusive and shadowy one, so far as records of his journeys are concerned. He, too, like Pennant’s hardy single gentlemen, commonly rode horseback, and has left traces of his presence here and there along the road, generally in witty and biting epigrams, written with a diamond ring on the windows of wayside inns. There could scarce, at this time, be anything more naïvely amusing than the pleased surprise he exhibits in a letter written to Pope in 1726, at “the quick change” he made in seven days from London to Dublin “through many nations and languages unknown to the civilised world,” when he had expected the enterprise, “with moderate fortune,” to occupy ten or eleven. “I have often reflected,” he adds, “in how few hours with a swift horse or a strong gale, a man may come among a people as unknown to him as the antipodes.”
The question, “How far to Holyhead?” had in old days been a difficult one to answer. It was not only in the uncertainty and variety of routes that the difficulty of accurately measuring the number of miles lay, but in the wild and conflicting ideas as to what really constituted a mile. This uncertainty lasted until the middle of the eighteenth century, when the first milestones since the days of the Romans were erected. It was, in fact, not before 1750, when, as part of their statutory obligations, the numerous Turnpike Trusts began to erect their milestones, that distances began to be publicly and correctly measured. It had already long been known that the mileages computed by the Post Office, in dealing with postmasters and the mails, were very inaccurate throughout the country, and for many years previously compilers of road-books had been accustomed to print two tables of distances; one the “computed” and Post Office mile, and the other the measured mile.
The first of English makers of road-books, John Ogilby, mentioned this discrepancy, so early as 1675, when he published his great work, _Britannia_. Ogilby who had been commissioned by Charles II. to survey the roads and measure them, did his work thoroughly. He claims to have travelled 40,000 miles in compiling his book, a folio volume of great typographical beauty and exquisitely engraved plans of the roads. In making his survey, he used what he calls a “wheel dimensurator.” Exactly what this was is shown in the beautifully etched title-page by Hollar, to his first edition, where Ogilby himself is seen on horseback, directing the course of two men; one wheeling the instrument, the other checking its measurements. It apparently was a wheel fitted with a handle and wound with a ten-mile length of tape. Trundled along, it unwound the tape, the intermediate distances being noted down by the assistant. Ogilby very soon discovered that although the Post Office gave the mileage to Birmingham and Holyhead respectively as 89 and 208 miles, it was then really 116 and 269 miles. The Post Office mile, which he calls the “vulgar computation,” was therefore practically a third larger than our so-called Statute Mile, dating from 1593 and constituted by a statute of the 35th year of Queen Elizabeth’s reign, not so much for the purpose of creating a standard of measurement for the kingdom, as for defining certain limits. That Statute was passed by a Legislature dismayed by the rapid growth of London, and was an enactment forbidding persons to build within three miles of the capital. When it came to the point of defining a mile, it was found that no such measure had ever been officially fixed, and that English, Irish, Scottish, and local miles were of variable lengths. The mile was then taken to be eight “forty-longs,” or furlongs, of forty perches each; a perch to consist of 5½ yards.