i 3 4 THE POPULAR SCIENCE MONTHLY
or universities : that these discoveries on British soil, like those involved in the theories of Newton, Harvey and Young, were taken up in Paris by members of the Academy of Sciences and through the aid of the government and by means of a wise organization of students of science were tested and their value made known to the world. It is to LaPlace of the Paris Academy of Sciences, more than to any one else, that New- ton's theories were made known and were at last universally accepted. Paris up to the middle of the nineteenth century was the most impor- tant center of organized scientific study in the world. It was here that the experiments of Lavoisier in chemistry were made, here that Cuvier, Arago and scores of other men introduced into their studies the methods of exact measurements and weights, brought scientific pro- cedure to mathematical precision and stated results in mathematical formulas. It was in Germany, in the universities rather than in the academies, that these results were recorded, and through numerous periodicals given to the world. Germany long has been, and still is, the country of year books in which the history and progress of each special science is carefully traced and preserved for the benefit of the scholar. In France pains were taken with the literary form in which scientific discoveries were published, and a popularity was thereby secured for them unknown either in England or in Germany.
Two factors enter into intellectual progress, the extension or increase of knowledge, and its condensation. Eeports of discoveries in any de- partment of learning must be reduced to their lowest terms, or they will not be read, much less studied and made of use. In its accumulations of knowledge the nineteenth century is unsurpassed, but in condensa- tion of knowledge some think it inferior to the time of Pericles in Athens. Nor is it certain, others say, that during the Kenaissance, Italy did not surpass anything done in our modern era, and many give the palm to Prance during the sixteenth and seventeenth centuries. But the nineteenth century has no rival in its success in discovering and marking out new and better methods than any previously known, for increasing knowledge. It was in that century that the important con- ception of the unity of knowledge became prominent. In the opening of the twentieth century the desire to discover truth has not lost in strength, but our students and thinkers are exceedingly careful in the examination of the criteria of truth, for they have learned that not all which seems true, or is proclaimed as true, is true and can be accepted as true. Still men of science are wont to speak of their methods of study as " exact," and to call their discoveries " exact truth." The truths involved in these discoveries are tested by being brought into con- tact with practical life, that is, tested by experience. In all this thought is present and prominent. It is the thinker in the laboratory, in the factory, in the new industry established as the outcome of years