the movements of the stars either out of curiosity, or to note the passage of time. Astronomy would have had an early origin even if it had not been for the overflow of the Nile, yet it is doubtful if it would have developed so soon under different atmospheric conditions.
The commonest laws of physics as well as the simplest movements of the heavenly bodies were known so early that we are unable to trace their sources. The Egyptians, again, were probably the first to study physical laws. The pyramid builders must have had a considerable mechanical as well as astronomical knowledge. Later engineering feats, such as the canal of Ramases and the various contrivances for controlling the waters of the Nile, would be considered creditable achievements even at the present day, and hence they show considerable advance in engineering skill and in knowledge of physical laws. Thus a knowledge of physics seems to be traceable in early times to building enterprises and engineering achievements.
In ancient times the subject of chemistry was cultivated in a practical way in the shape of metallurgy, the manufacture of colored glass and the dyeing of fabrics. But interest was early turned aside from these practical problems to the visionary one of transforming the baser metals into gold. This quest of the alchemists was begun in ancient Egypt and was continued through the middle ages until the scientific awakening of the sixteenth century. On the whole it was more of a hindrance than a help to the development of chemical knowledge. A more profitable study lay in the search for curative agents. This first took the fanciful form of a search for the elixir of life, but after the time of Paracelsus in the sixteenth century, a more scientific attitude was fostered and medicine became the chief medium for the advancement of chemical knowledge. Up to the nineteenth century the only laboratory of chemistry was the pharmacist's shop. In comparatively recent times chemistry has found another incentive to progress in the desire to improve agriculture.
In their origins, chemistry and biology are more closely allied than any of the other sciences. Some knowledge of both animals and plants was of course gained in prehistoric times in the search for food. But in ancient civilizations and even down to modern times the one great stimulus to the growth of biological knowledge lay in the healing art. In ancient and medieval times almost all the contributors to biological knowledge were physicians with the possible exception of Aristotle, though it is doubtful if an exception should be made of a man who kept a pharmacy shop. At the Alexandrian museum the subjects of natural history and anatomy were carried on by the faculty of medicine, one of the four faculties originally established at the museum. In addition
- Wm. H. Welch, "The Interdependence of Medicine and Other Sciences of Nature," Science, January 10, 1908.