Page:Popular Science Monthly Volume 38.djvu/152

142 kinds of artifices in order to acquire speed prior to flapping their wings: some run on the ground before darting into the air, or dart rapidly in the direction they wish to take in flying; others let themselves fall from a height with extended wings, and glide in the air with accelerated speed before flapping their wings; all turn their bill to the wind at the moment of starting."

Origin of Warts on Forest Trees.—The formation of abnormal growths—knots or warts—on forest trees, which are very common on some species, is thus accounted for by Robert Cowpar in Science Gossip: "They are not due to insects, fungus, or accident, but are perfectly natural. Neither may they be taken as indications of health or disease, nor are they in any way attributable to any particular soil or situation. . . . In the barks of our forest trees are contained a multitude of latent buds which are developed and grow under certain favorable conditions. Some trees possess this property in a remarkable degree, and often, when the other parts are killed down by frost in severe winters, the property of pushing out these latent buds into growth preserves the life of the plant. These buds, having once begun to grow, adhere to the woody layer at their base, and push out their points through the bark toward the light. The buds then unfold and develop leaves, which elaborate the sap carried up the small shoot. Once elaborated, it descends by the bark, when it reaches the base or inner bark. Here it is arrested, so to speak, and deposited between the outside and inner layer of bark, as can be learned on examining specimens on trees in the woods almost anywhere."

Value of Phenological Observations.—Phenological observations of plants, or observations of the time of the first appearance in the year of the several stages of growth, have long been recognized as useful in the study of climates. A phenological observer may in five years determine approximative means for judging of the succession of each of the phases of vegetation. When we have ascertained the mean time of the occurrence of the principal changes for five years, as, for instance, when the first apple blossoms open in the immediate vicinity of the station, or the first fields of barley are cut, we are then able to judge how the station comports itself relatively to any other station of which the phenological position is fixed; and how each point of a region comports itself relatively to the principal point—whether it is colder or warmer. This is determined by the stage of vegetation which the same plants have reached here and there. The method is really more exact than that of establishing hundreds of thermometers and pluviometers at as many different places—aside from the trouble and expense of keeping up the observations of so many instruments. Phenology goes on without expense, while meteorology is costly. We are able, every year and every week in the year, to compare observations of vegetation with means that have been established, and assure ourselves whether the vegetation at our station is normal or in advance. Phenology is a kind of thermometry that can also be used to test thermometrical observations and correct erroneous conclusions from them. The plant is a sort of registering thermometer. It, in fact, shows us the present condition, as the thermometer does, and likewise all the conditions of the past time, immediately summed up in a final result, while the thermometer simply gives us the daily oscillations and leaves us to make the summing up. Phenological observations, with figures founded on comparisons, have the advantage of raising the thought of relation in the mind, of representing something tangible to it.

Ancient Fireplaces on the Ohio.—The ancient fireplaces at Blue Banks and other places on the Ohio River near Portsmouth are described by Mr. T. H. Lewis as being of three different classes. Those on the lower levels only show a burned streak of clay from five to eight feet in diameter, with but a slight concavity, on which are found ashes, charcoal, burned stones, and bones, with an occasional fragment of pottery, composed of broken stone and clay. Many of them, at the level of twenty feet from the surface, where they are most numerous, are from one to three feet deep, and are lined with flat stones. The clay outside of the stones bears evidence of intense heat. In some instances they are nearly filled with ashes and charcoal. The pottery within them is composed