An Odometer, Pedometer, Perambulator, or Way-measurer, is an instrument or machine by which the steps of a person who walks, or the revolutions made by the wheel of a carriage, can be counted, and by which the distance that one has travelled can be ascertained. Vitruvius, in his tenth book[15], describes a machine of this kind for a carriage, and which, in his opinion, would answer for a ship. We are told by Capitolinus, in the life of the emperor Pertinax, that among the effects of the emperor Commodus exposed to sale, there were carriages of various kinds, some of which “measured the road, and pointed out the hours;” but whether by these words we are to understand an odometer, cannot with certainty be determined. That this instrument was known even in the fifteenth century, can be proved from the carving on the ducal palace at Urbino--an edifice erected in an uncommon style of magnificence, by duke Frederic, who died in 1482. The ornaments here employed form, almost, a complete representation of all the warlike apparatus used at that period, both by sea and land; and among these is the figure of a ship, which seems to be furnished with an odometer; but whether the wheels and springs, carved out apart, be intended to show the construction of it, I will not venture to decide[16]. The celebrated John Fernel, physician to Catherine of Medici, queen of France, measured with an instrument of this kind, in 1550, a degree of the meridian between Paris and Amiens, and found it to be 68,096 geometrical paces, or about 56,747 toises (364,960 English feet); that is, 303 toises less than Picard found it to be; or about 300 toises less than later measurements have made it. Picard himself, in his mathematical measurement, assisted by the newest improvements, erred 123 toises. It is therefore very surprising that Fernel should approach so near the truth with such an instrument. The manner of constructing it however, as far as I know, appears to be lost[17]. Levin Hulsius, in his Treatise of mechanical instruments, published at Frankfort in 1604, describes an odometer, but without naming the inventor. It appears, however, that it was the production of Paul Pfinzing, born at Nuremberg in 1554[18]; and who, besides other works, published, in 1598, Methodus Geometrica, or a Treatise on measuring land, and how to use proper instruments for that purpose, on foot, on horseback, or in a carriage. This treatise, which was never sold, but given away by the author, contains a description of the same instrument described by Hulsius, and which, as Nicolai says, is still preserved in the collection of curiosities at Dresden.