But it is allowable for us, when we have done our best in collecting and examining phenomena, to arrange them together according to any plausible theory which our judgments can suggest. Still, however, we ought to remember, that the most obviously imperative dictates of our reasoning faculties are only inferences from present appearances, and determine nothing as to the necessity of existing things.--E.] If former navigators have added more land to the known globe than Captain Cook, to him, at least, was reserved the honour of being foremost in disclosing to us the extent of sea that covers its surface. His own summary view of the transactions of this voyage, will be a proper conclusion to these remarks: "I had now made the circuit of the southern ocean in a high latitude, and traversed it in such a manner as to leave not the least room for there being a continent, unless near the Pole, and out of the reach of navigation. By twice visiting the Tropical Sea, I had not only settled the situation of some old discoveries, but made there many new ones, and left, I conceive, very little to be done, even in that part. Thus I flatter myself, that the intention of the voyage has, in every respect, been fully answered; the southern hemisphere sufficiently explored; and a final end put to the searching after a southern continent, which has, at times, engrossed the attention of some of the maritime powers for near two centuries past, and been a favourite theory amongst the geographers of all ages."[31] [Footnote 31: Cook's second Voyage.] Thus far, therefore, the voyages to disclose new tracks of navigation, and to reform old defects in geography, appear to have been prosecuted with a satisfactory share of success. A perusal of the foregoing summary of what had been done, will enable every one to judge what was still wanting to complete the great plan of discovery. The southern hemisphere had, indeed, been repeatedly visited, and its utmost accessible extremities been surveyed. But much uncertainty, and, of course, great variety of opinion, subsisted, as to the navigable extremities of our own hemisphere; particularly as to the existence, or, at least, as to the practicability of a northern passage between the Atlantic and Pacific Oceans, either by sailing eastward, round Asia, or westward, round North America.