Columbus discovers America / Winsor, J. -- Arrival at the Pacific ocean, 1805 / Lewis and Clarke -- The sources of the Mississippi, 1806 / Pike, Z. M. -- Manila in 1842 / Wilkes, C. -- The ascent of Mount Tyndall / King, C. -- The grand cañon of the Colorado is explored / Powell, J. W.
magnets were used, which had lost their power to point correctly to the pole. Others had contended that it was through insufficient application of the loadstone to the iron that it was so devious in its work.
What was thought possible by the early navigators possessed the minds of all seamen in varying experiments for two centuries and a half. Though not reaching such satisfactory results as were hoped for, the expectation did not prove so chimerical as was sometimes imagined when it was discovered that the lines of variation were neither parallel, nor straight, nor constant. The line of no variation which Columbus found near the Azores had moved westward with erratic inclinations, until to-day it is not far from a straight line from Carolina to Guinea. Science, beginning with its crude efforts at the hands of Alonzo de Santa Cruz, in 1530, has so mapped the surface of the globe with observations of its multifarious freaks of variation, and the changes are so slow, that a magnetic chart is not a bad gu