The first expense noted in the account books belonging to Magellan's fleet was for money sent to Biscay for Captain Artieta of Lekeitio. They sent 1,500 gold ducats - some 750,000€ at today's rate, under direct orders from the king, who advised the officials at the Contracting House that the best supplies for the fleet were to be found in Biscay, at the best prices.
Of the five ships in the fleet, three were from Biscay: the Trinidad, the San Antonio and the Victoria. Document number 15 shows that the Victoria, in proportion to her tonnage, was much more expensive than the other two. One hypothesis is that the Victoria was the newest of the three.
By using the astrolabe's scale and quadrant, the height of the sun over the horizon at midday could be calculated. The resulting measurement was then subjected to a series of complex rules before positioning the ship on the north-south axis. At night, the same operation could be made using the pole star or the southern pole star (the South star), depending on which hemisphere they were in.
The skill of a ship's pilot in obtaining precise measurements seems almost unbelievable. We have evidence from the year 1500, where an expert in astronomy assures his readers that, due to the rocking of the boat, it was impossible not to err by at least 4º - or nearly 500 kilometres.
The sea-farer's needle is one of the most useful instruments for navigation. By day or by night, in clear or overcast weather, it continues to show the true path across the water.
The sea-farer's needle was, without doubt, the most important instrument to navigate by. It was magnetised with a "magnetic stone", known today as magnetite. It has always been said that a magnetised needle points north, but in reality a compass is composed of two conjoined needles, one pointing north and the other pointing south. This is made possible by using one end of the magnetic stone to magnetise the north-pointing needle, and the other end to magnetise the south-pointing one.