remain a source of wonder to moderns. If we may believe all that students of the pyramids tell us, the Egyptians had no mean knowledge of astronomy as well. Certain it is that the Assyrians had a knowledge not only of astronomy, but of mathematics, having highly developed systems of numeration and methods of calculation, their sexagesimal system of numeration having come down to us in the division of the circle into three hundred and sixty degrees, against which anachronism the decimal system is but now beginning to struggle. The engineering operations of the Egyptians, however, were of a very simple sort, and their construction of the pyramids was probably permitted rather by the unlimited supply of forced labor than by the employment of devices for taking advantage of anything but brute force.
As the Hebrews were specialists in morals, so the Greeks were specialists in beauty, and pushed its culture to a degree never before or since attained. Had the Greeks left to us no masterpieces of literature, we should forever remember them by their magnificent temples, their incomparable sculpture, and their beautiful vases. Such a people must inevitably have had great thoughts to express in prose and verse, and it is not surprising that they were sensible of the beauties of the intellect, and pushed the study of geometry to a very considerable extent. The value which they attached to this study may be inferred from the inscription over the door of Plato's academy, "Let none enter who is not a geometrician," a motto which, by the way, I would gladly see placed over the gate of the modern college. Archytas of Tarentum, about 400 b.c., had devised apparatus for constructing various curves, had recognized the spherical form of the earth, and its daily rotation. Aristotle wrote a voluminous treatise on animals, showing careful observation of their habits, and even left a treatment of mechanical problems in which he almost recognizes the nature of the parallelogram of motions and of centrifugal force. In the domain of physics, however, he is not particularly happy, and is better at asking questions than in solving them. A hundred years later, however, Archimedes, the greatest of the Greek scientists, not only makes great advances in geometry, including a method that is in a measure the precursor of the integral calculus, but displays an acute knowledge of the principles of statics, including the principle of the lever, and of the fundamentals of hydrostatics, especially the principle named after him. With Archimedes, as with the other Greek philosophers, the practical applications accompanied, and probably generally preceded, the theoretical inquiries, and indeed this is still usually the case. The Romans, who succeeded the Greeks in importance in the ancient world, certainly did not do so on account of their cultivation of scientific studies, in which they played a poor part. Their very clumsy system of numeration would show their lack of mathematical talent, but on the other hand their extremely prac-
