It seems probable that the magnetic compass, the mariner's compass as it is often called, first made its appearance at some time between the tenth and twelfth centuries A.D. Attempts have been made to prove that the compass was in existence earlier, and that some of the early voyages could not possibly have been performed without its help; but there is no evidence to support this contention and a certain amount to show that other methods were used.

Again, it has been suggested that some obscure remarks by certain classical writers could be explained if the author were assumed to be describing the use of a compass, whilst having only the haziest notion of what it was. Among such is the legend of Abaris, the Hyperborean priest, who visited Greece, some say from Britain, many centuries B.C., and had with him a mysterious arrow which showed him the way. If we cut out the fancies of some writers who credited him with the possession of a kind of aircraft (capable of supersonic speeds), it is not difficult to imagine that the arrow may have been a magnetized needle. The difficulty is in understanding how no one down the centuries which followed came to write of the compass. There is, of course, little doubt that much scientific knowledge was possessed by the ancient priestly cults and the knowledge of the compass may have been kept secret for their own ends. If the great library of Alexandria had not been destroyed we might have had the answer to the riddle; but perhaps there is none and the whole tale of Abaris is a fabrication.