OBSERVATION AND EXPERIMENT are the leading features of modern science, as contrasted with the philosphy of the ancients. They are indispensable as the bases of all human knowledge, and no true philosophy has ever made progress without them, either consciously or unconsciously exercised. Thus, by Socrates, Plato, and Aristotle, no less than by Archimedes and the ancient astronomers, observation and experiment are extensively though not prominently or always obviously employed; and it Was by losing this clue to the spirit of their master's teaching, that the later disciples in these schools of philosophy missed the path of real progress in the advancement of knowledge. It was in the latter half of the 16th c. that the minds of philosophers were first consciously awakened to the importance of observation and experiment, as opposed to authority and abstract reasoning. This result was first by the discoveries and controversies of Galileo in Florence; nod to the same end were contributed the simultaneous offorts of a number of philosophers whose minds were turned in the same direction—Tycho Brahe in Holland, Kepler in Germany, William Gilbert in England, who were shortly after wards followed by a crowd of kindred spirits. The powerful mind of Francis Bacon lent
itself to describe the newly awakened spirit of scientific investigation, and though he ignored or affected to despise the results achieved by the great philosophers just men tioned, he learned from them enough to lay the foundation of a philosophy of inductive science, which, if we look at the course of scientific progress since his day, seems to have been almost prophetic. The difference between observation and experiment may be said to consist in this, that by observation we note and record the phenomena of nature as they are presented to us in her ordinary course; whereas by experiment we note phe nomena piesented under circumstances artificially arranged for the purpose. Experiment is thus the more powerful engine for discovery, since one judiciously conducted experi ment may provide the data which could only result from a long course of observations.