520 



SCIENCE 



[N. S. Vol. XXXVIII. No. 980 



of the International Commission for Scien- 

 tific Aeronautics in Vienna, May 27-June 1, 

 1912,° proposed (1) that the results of upper- 

 air observations shall be arranged according 

 to definite steps of pressure instead of steps of 

 height; (2) that the heights shall be given in 

 " dynamic meters," i. e., a step corresponding 

 with a certain difference of gravity potential, 

 not of geometric height; (3) that pressures 

 shall be recorded in millibars (C.G.S. units), 

 instead of in millimeters or inches. There 

 was so much objection against a change of 

 units, that the Meteorological Committee re- 

 solved that, for the present at least, aerologieal 

 pressure results should be published both in 

 millimeters and in millibars. The substitution 

 of pressure steps for linear steps was favorably 

 passed upon, but the proposition as to " dy- 

 namic meters " was referred back to the com- 

 mission at the request of its president. Dr. 

 Hergesell, for further consideration. 



On the recommendation of the radiation 

 commission, it was resolved that specifications 

 as to sunshine recorders be drawn up, to fa- 

 cilitate comparison between sunshine records 

 in different countries. 



The resolution of the Paris conference 

 (1896), calling for the standardization of 

 thermometer exposure, was discussed and tests 

 of English thermometer shelters in the tropics 

 were recommended. 



A system of sig-nals for international use 

 was recommended by the Commission on 

 Maritime Meteorology and Storm-warning Sig- 

 nals, and accepted by the Meteorological Com- 

 mittee with a few minor changes. Thus a sub- 

 stantial measure of international agreement 

 on day and night storm-warning signals has 

 been attained. 



The , next conference of the committee will 

 come in 1915, in Holland. 



EVAPORATION FROM LAKE SURFACES 



In the Meteorologische Zeitschrift for May, 

 1913, Dr. J. Maurer, director of the Swiss 

 Weather Service, gives the results of his meas- 

 urements of evaporation from the surfaces of 

 Lakes Zuger and Ageri in northern Switzer- 



' See Nature, London, Vol. 90, p. 110. 



land, December, 1911-lSrovember, 1912, inclu- 

 sive. By the method used, the evaporation ia 

 the difference between the amount of water 

 entering a lake and that flowing out, if the 

 water-surface level remains constant. The 

 amount entering in streams was determined 

 as closely as possible by frequent measure- 

 ments of the cross-sections and velocities of 

 the streams flowing into the two lakes. To 

 these the amounts of rainfall on the lake sur- 

 faces were added. The water flowing through 

 the outlet streams was also carefully meas- 

 ured. With the aid of measurements of the 

 variations in height of the lake surface as 

 indicated on gauges for the purpose, the re- 

 sults from the other measurements could be 

 checked to some extent. The totals of monthly 

 evaporation are probably correct within 0.5 

 cm. The unknown amount of gain or loss 

 of water through the lake bottom was disre- 

 garded, for, on the whole, these lakes have im- 

 pervious basins and no large springs are 

 known. Supplementary observations of the 

 temperature of the water surface, humidity at 

 the water surface, and of the air-temperature, 

 wind, cloudiness, etc., were taken at selected 

 points. In 1912, a year with a cool and rainy 

 August and September, the measurements 

 showed an evaporation of 775 mm. from 

 Zuger Lake (417 m. above sea level, area 34 

 sq. km.) and 740 mm. from Ageri Lake (727 

 m. above sea level, area 7 sq. km.). In a year 

 with a normal summer, the annual evapora- 

 tion would probably exceed 900 mm. These 

 interesting results are the first of their kind 

 yet published, and bid fair to lead the way for 

 other similar measurements on lakes and 

 reservoirs elsewhere. 



VOLCANOES AND CLIMATE 



The solar radiation observations of Messrs. 

 C. G. Abbot and F. E. Fowle" and Professor 

 H. H. Kimball* show that the Katmai volcanic 

 dust cloud in the atmosphere in the summer of 

 1912 in the northern hemisphere, so increased 

 diffuse reflection into space and absorption of 

 heat in the upper atmosphere, that the normal 



° ' ' Volcanoes and Climate, ' ' Smithsonian Misc. 

 Coll., Vol. 60, No. 29. 



* Mt. Weather Bull, Vol. V., Part 5. 



