Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.2): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

48 ZERO FOR LONGITUDE — SANTA CRUZ. Jan. island, or on board a ship in the ofRng, except by a trigono- metrical process, always open to errors. Indeed the summit of the peak is not visible from the east, on account of intervening land, until the observer is at some distance from the shore. Hence all meridian distances measured from Teneriffe must depend upon the degree of accuracy with which the position of the actual starting-point, with respect to the Peak, was deter- mined. How many errors have been caused in ascertaining the lon- gitudes of distant places, by a mistake in the longitude of the position from which a ship, or an observer, actually departed ! How many discrepancies between the measurements of different nations would vanish, if the precise points from which each observer set out were known; and if the positions of those points, with respect to one another, were accurately verified ! About noon we approached the sun-burned, uninviting town of Santa Cruz. Lying upon a level, arid space, at the foot of hills, that rise slowly to a considerable height, so as to shut out the more elevated part of the island ; hardly a tree to be seen, and no appearance of cultivation ; guarded by a rocky shore, on which there is always a disagreeable — often a danger- ous surf; it offers indeed little to tempt delay. But notwith- standing this unpromising exterior, and a port so exposed that Spanish ships of war were ordered by their Government to moor there with four anchors, there is much to be found in the higher and interior parts of Teneriffe which amply repays the labour of ascending to and exploring those regions. In one of the churches in Santa Cruz is still hanging the remains of a flag, taken from the English, or left behind, when Nelson lost his arm. Our anchor had just touched the ground, when a boat from the Health Office approached nearly along-side, conveying the British vice-consul and some quarantine officers, who told us, after hearing whence we came, that it would be impossible to grant permission for any person to land ; and that until we should have performed a strict quarantine of twelve days' dura- tion, no personal communication could be expected. This