Page 79 - Dutch Asiatic Shipping Volume 1

(3471, 3952) from time to time, just as before, and again after. In all cases these were ships trying to cross the equator in the unfavourable season, having left the Republic in April, May or June.
In spite of all detailed descriptions of the wagenspoor, the one great navigational pro- blem remained insurmountable that in critical situations it was not possible to determine accurately the longitude of the ship's position. The instructions of 1627 and 1654 contain indications of the number of miles from for instance point A to a given place, or only the latitude. Those of the eighteenth century give latitude and longitude for all points of the wagenspoor. To establish the latter the zero meridian across Tenerife in the Canaries was used. Compass variations in the area were collected on a large scale, but guessing at the longitude still remained the starting point. More than ever before masters were advised to observe the nature of the changeable winds and currents around the 'middle line'. Only towards the end of the Company's trading in 1788, a proper method of calculating longitude could be introduced.18
The wagenspoor was of importance only to ships crossing the equator between June and October, belonging to the fleets which left home during the spring or later. The instructions for the autumn sailings contained but a few words indicating its existence, except for those of 1748, which advised ships to cross the Line between points C and G .
Once having arrived in the southern hemisphere and having passed the easternmost point of Brazil, ships crossed the western part of the Atlantic with a favourable wind and current. From around thirty degrees south they made for the Cape.
c. Ports of call
In 1616 it was decided that the only port of call on the way to Asia was to be the Cape of Good Hope. But in practice this rule was not always obeyed. Though ports in the Gulf of Guinea became less frequented, partly due to the sailing instructions, yet in 1639 the Hoge Regering in Batavia gave warning to the Heren Zeventien in the matter of four ships (0528-0531) which had not yet arrived, that 'in case these souls have gone boating in the Gulf of Guinea, Your Honours may expect the officers back as deportees!'19
Only one particular group of ports on the Atlantic run was never subject to strict regulations. They were the Cape Verde Islands which lay right on course. The northeast trade wind took Asiatic shipping as well as traders with Brazil and parts of the West Indies into this area. The ten largest islands made natural ports of call or points of rendez-vous.
This archipelago, also known as the Salt Islands, was not rich in vegetation. It lacked an indigenous crop, the only fresh provisions that could be obtained here being dried or salted goats' meat and some fruits. There was a scarcity of drinking water. Rainfall was limited to a few months in late summer. Five of the islands were particularly dry: S. Vincente, Sal, Maio, Boavista and S. Luzia. The other five: S. Tiago, Fogo, Brava, S. Nicoiao and S. Antâo had more rainfall and vegetation. Though it seems unlikely that great climatic changes were taking place, it appears that the East Indiamen gradually began to avoid the drier islands of Maio and S. Vincente and that after 1680 particularly
18 Voorbeijtel Cannenburg, 'Het 'Karrepad", 467-471, Mauro, Le Portugal, 24 (map); Heeres, 'De 'Consideration", 567. Copies of the various instructions can be found in A R A , V O C archives and in the library of the Nederlands Scheepvaartmuseum in Amsterdam, among others. In the 1768 and 1770 editions for instance points H and I are still included, because of new attention given to the use of compass variations, see also Davids, 'Commentaar', and his book mentioned in chapter 6, note 37.
19 ARA,VOC 450, 8.12.1616. Coolhaas, Generale Missiven II, 89.