Page:Popular Science Monthly Volume 59.djvu/309

Rh designed to remedy this defect has been performed under artificial indoor conditions. These Blue Hill investigations showed plainly the necessity for greater uniformity in anemometers both as regards shape and size. The fan or bladed anemometers, with the use of ball bearings, seem to have many advantages over the ordinary cup anemometers now so generally used. There was found to be still much room for improvement in the pressure wind gauges, as those at present in use are not thoroughly satisfactory. The pressure tube anemometers, upon which many hopes have been built, showed need of some further modifications before it will be perfectly adapted to all conditions of wind and weather. Concerning the standardizing and testing of anemometers under artificial conditions, the opinion is advanced that a current of air produced by a blower is more likely to give absolute results than the whirling machine at present in use.

Among the important general meteorological questions taken up are the following: (1) The investigation of the temperature indications of thermometers placed in different kinds of thermometer shelters or screens. (2) The study of special phenomena exhibited by the records of self-registering meteorological instruments; such, for instance, as the dynamic effect of the wind on barograph records. (3) The study of weather predictions, from both the central and local points of view, and the demonstration that the combination of the two methods gave the best results. (4) The study of sudden falls of temperature and their relation to general atmospheric conditions. (5) The study of wave-like oscillations shown in the records of barometric pressures. (6) Studies concerning the periodicity of the weather. (7) The discussion of cloud observations, especially those made at the Blue Hill Observatory. (8) The improvement of meteorological apparatus, especially in the self-registering devices, and adapting the existing instruments to special needs. (9) The study of special cloud forms. (10) Cooperative study of clouds during the International 'Cloud year.'

That the movements of the atmosphere follow on certain laws we all recognize. Some of these laws we know, others remain still to be discovered. No work of the Blue Hill Observatory has exceeded in importance its studies of the actually observed movements of the air, and the so-called dynamic changes which these movements cause the air to undergo. In nearly every phase of this many-sided question this observatory has increased our stock of knowledge.

The study of the upper atmosphere was early begun by the staff of the Blue Hill Observatory, At first it was mainly carried on by means of cloud observations, but since 1894 by means of registering meteorological instruments carried aloft by kites. To this observatory belongs the honor of thus sending up into the air the first continuously