THE BLUE HILL OBSERVATORY. 299 



tion 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 improve- 

 ment 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 indica- 

 tions 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 tem- 

 perature 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 



