Page:Popular Science Monthly Volume 38.djvu/153

Rh of shell and clay. At a higher level, the fireplaces, while not so numerous, are more interesting, because more or less of fire relics are obtained from them. They are only slightly concave, and mixed with the ashes are stones broken by the action of fire, bones of various kinds, arrow-heads, drills, stone and hematite celts, stone pipes, perforated stones called shuttles, and much broken pottery. These places seem to have been occupied at different times, and also by different tribes or nations. The first occupants used stone in the manufacture of their pottery. They were succeeded by others who used shells, and these in their turn gave way to people using stone. The latter seem to have occupied the ground for only a brief period, and then to have been displaced by others using shell. In the adjoining field, however, both kinds of pottery are found intermingled. It is Mr. Lewis's opinion that the people of these fireplaces antedated the residence of the mound-builders in their neighborhood by many centuries, because the works of that race, themselves very ancient, are found on the surface above them. The fireplaces occur at various levels, from near the top of the bank to thirty feet below. At one point they were visible at seventeen different levels. They are exposed to view by the caving off of the banks at high water. A somewhat similar series of fireplaces or ovens was described in the American Association by Prof. Putnam as observed on the banks of the Little Miami River.

Cold Waves.—According to Prof. T. Russell's explanation of the subject, in the American Association, the term cold wave is employed when a fall of temperature occurs in twenty-four hours of 20° or more over an area of at least 50,000 square miles, and the temperature in any part of the area descends to 36°. According to this definition, there were in the United States, between 1880 and 1890, 691 cold waves. In the great cold wave of January 17, 1882, the twenty-degree fall line included an area of 1,101,000 square miles, and the ten-degree fall line an area of 2,929,000 square miles. There have been in ten years six cold waves in which the area of the twenty-degree fall was more than a million square miles. The cold waves seem always to occur over the country covered on the preceding day by an area of low barometric pressure, or the southeast of the country covered by an area of high pressure. Where both occur, the cold waves attain their greatest extent. Only a few cases are recorded in which low pressure areas have not been followed by a fall of temperature at their centers. In twelve instances within ten years there were rises in temperature instead of falls. On the other hand, cold waves do not occur without the presence of an area of high or low pressure. The extent of the cold wave is dependent on the extent of the area of low pressure and the area of high pressure on the day preceding it. The shapes and relative positions of areas of high and low pressure are various, and are described and classified in the author's paper.

The Forest.—In a paper read at the American Association Prof. B. E. Fernow said that the forest is both a material resource and a ' cultural condition. While it may and does form the object of individual activity, it also can by its location or position become an element influencing climate, soil, and waterflow. The climatic influence of forest areas is as yet not generally proved, although conditionally accepted, but the influence of forest areas upon the waterflow, and with it upon soil conditions and upon winds, is generally recognized. As a material resource the forest is exhaustible, but restorable within limit. The virgin forest must be reduced to get the agricultural ground that is needed, but when the requirement for food is satisfied it is desirable to treat the forest in such a manner as to secure continued reproduction. This gives rise to forest management and forestry as an industry. Reproduction of the natural forest is inferior in quality and quantity to that which can be produced by national forest management. After mentioning some special considerations and economical peculiarities pertaining to forest growth and forestry which may influence the relation of the state toward them, the author went on to say that, so far as the forest represents a material resource simply, the position of the state toward it need not differ from that which it takes toward other industries and