APPENDIX. Note to Preface, p. xx. HERSCHEL on the Study of Natural Philosophy. Lardner's Cabinet Cyclopædia, No. 14, p. 67. We have thus pointed out to us, as the great, and indeed only ultimate source of our knowledge of nature and its laws, EXPERIENCE; by which we mean, not the experience of one man only, or of one generation, but the accumulated experience of all mankind in all ages, registered in books or recorded by tradition. But experience may be acquired in two ways: either, first, by noticing facts as they occur, without any attempt to influence the frequency of their occurrence, or to vary the circumstances under which they occur; this is OBSERVATION: or, secondly, by putting in action causes and agents over which we have control, and purposely varying their combinations, and noticing what effects take place; this is EXPERIMENT. To these two sources we must look as the fountains of all natural science. It is not intended, however, by thus distinguishing observation from experiment, to place them in any kind of contrast. Essentially they are much alike, and differ rather in degree than in kind; so that, perhaps, the terms passive and active observation might better express their distinction; but it is, nevertheless, highly important to mark the different states of mind in inquiries carried on by their respective aids, as well as their different effects in promoting the progress of science. In the former, we sit still and listen to a tale, told us, perhaps obscurely, piecemeal, and at long intervals of time, with our attention more or less awake. It is only by after-rumination that we gather its full import; and often, when the opportunity is gone by, we have to regret that our attention was not more particularly directed to some point which, at the time, appeared of little moment, but of which we at length appreciate the importance. In the latter, on the other. hand, we cross-examine our witness, and by comparing one part of his evidence with the other, while he is yet before us, and reasoning upon it in his presence, are enabled to put pointed and searching questions, the answer to which may at once enable us to make up our minds. Accordingly it has been found invariably, that in those departments of physics where the phenomena are beyond our control, or into which experimental enquiry, from other causes, has not been carried, the progress of knowledge has been slow, uncertain, and irregular; while in such as admit of experiment, and in which mankind have agreed to its adoption, it has been rapid, sure, and steady. I. Page 6. Narrative of a visit to Brazil, Chili, Peru and the Sandwich Islands, during the Years 1821 and 1822, by Charles Farquhar Mathison, Esq. p. 449. The King then is a complete autocrat-all power, all property, all persons are at his disposal: the chiefs receive grants of land from him, which they divide and let out again in lots to their dependants, who cultivate it for the use of the chief, reserving a portion for their own subsistence. The cultivators are not paid for their labour, nor, on the other hand, do they pay a regular rent for the land. They are expected to send presents of pigs, poultry, tarrow, and other provisions, to the chief, from time to time, together with any little sums of money which they may have acquired in trade, or any other property which it may suit the fancy or the |