OCEANIC DISCOVERIES. Col 



his Arte de navegar, till the invention of the instrument 

 made by Martin Behaim in 1484 at Lisbon, and which was, 

 perhaps, only a simplification of the meteoroscope of his 

 friend Regiomontanus. When the Infante Henry, Duke of 

 Viseo, who was himself a navigator, established an academj 

 for pilots at Sagres, Maestro Jayme of Majorca was named its 

 director. Martin Behaim received a charge from King John 

 II. of Portugal to compute tables for the sun's declination* 

 and to teach pilots to " navigate by the altitudes of the sun 

 and stars." It cannot at present be decided whether, at 

 the close of the fifteenth century, the use of the log was 

 known as a means of estimating the distance traversed 

 whilst the direction is indicated by the compass ; but it is 

 certain that Pigafetta, the companion of Magellan, speaks of 

 the log (la catena a poppa), as of a well-known means of 

 measuring the course passed over.* 



* In all the writings on the art of navigation which I have examined, 

 I have found the erroneous opinion that the log for the measurement 

 of the distance traversed, was not used before the end of the sixteenth 

 or the beginning of the seventeenth century. In the Encyclopedia 

 Britannica (seventh edition, 1842), vol. xiii. p. 416, it is further stated, 

 " The author of the device for measuring the ship's way is not known, 

 and no mention of it occurs till the year 1607, in an East Indian voyage 

 published by Purchas." This year is also named in all earlier and later 

 dictionaries as the extreme limit (Gehler, bd. vi. 1831, s. 450). Navar- 

 rete alone, in the Dissertation sobre los progresos del Arte de Navegar, 

 1802, places the use of the log-line in English ships in the year 1577. 

 (Duflot de Mofras, Notice biographique sur Mendoza et Navarrete, 

 1845, p. 64.) Subsequently, in another place (Coleccion de los Viages 

 de los Espaholes, t. iv. 1837, p. 97), he asserts that, "in Magellan's 

 time the speed of the ship was only estimated by the eye (d ojo), 

 until, in the sixteenth century, the corredera (the log) was devised." 

 The measurement of the distance sailed over by means of throwing the 

 log, although this means must, in itself, be termed imperfect, has 

 oecome of such great importance towards a knowledge of the velocity 

 ind direction of oceanic currents, that I have been led to make it an 

 object of careful investigation. I here give the principal results 

 which are contained in the sixth (still unpublished) volume of my 

 Examen critique de Thistoire de la Geographic et des pr ogres de 

 I Astronomic nautique. The Romans, in the time of the republic, had 

 in their ships way-measurers, which consisted of wheels four feet high, 

 provided with paddles attached to the outside of the ship, exactly as in 

 our steamboats, and as in the apparatus for propelling vessels, which 

 Blasco de Garay had proposed, in 1543, at Barcelona to the Emperor 



