Oct. 4, 1921 proceedings: philosophical society 397 



observer's reactions as "blue," "white," or "yellow," as the case may be. 

 The second method proved to be the more satisfactory. 



Experimental results were given from four observers. The average results 

 of these observers indicate that "white light" may be represented : (1) theoret- 

 ically, by the light from a Planckian radiator at a temperature of about 5200° 

 absolute; (2) practically, to a fair approximation, by average noon sunlight 

 at Washington. It is, however, emphasized that the final establishment 

 of such a standard should be based on a more extensive statistical investiga- 

 tion. 



The paper was discussed by Messrs. Gardner, HawkesworTh, Faris, 

 Burgess, Tuckerman, Sosman, and others. 



The complete paper is being published as a Bureau of Standards Scientific 

 Paper. 



852d meeting 



The 852d meeting of the Philosophical Society of Washington was held in 

 the Assembly Hall of the Cosmos Club, May 21, 1921. It was called to 

 order by President Faris with 36 persons present. 



The first paper, on Relation of coastal currents and winds on the Pacific 

 Coast was presented by Mr. H. A. Marmer and was illustrated. 



This paper presented the results of an investigation of the speeds and 

 directions of the current along the Pacific Coast of the United States brought 

 about by local winds. The investigation was undertaken primarily for the 

 purpose of aiding the mariner and was based on observations made under the 

 direction of the Coast and Geodetic Survey by members of the crews of the 

 five light vessels stationed along the coast from San Francisco Bay to the 

 Strait of Juan de Fuca. The apparatus used for measuring the speed and 

 direction of the current was necessarily the simplest, and consisted of a 15 foot 

 current pole, a log line graduated to knots and tenths for a run of one minute, 

 a stop watch, and a pelorus. The wind velocity was estimated in accordance 

 with the Beaufort Scale. 



Since the current as observed is the resultant of a number of different cur- 

 rents due to various causes, such as tides, winds, river discharge and differences 

 in density, the observations are tabulated with reference to various arguments. 

 Thus by tabulating with reference to time of tide at a nearby port for periods 

 of 29 days, the tidal current is derived. This current on the Pacific Coast, 

 off'shore, is of the rotary type, the direction of rotation being clockwise, and 

 shows considerable diurnal inequality. The wind current is derived by tabu- 

 lating the observations with reference to winds of particular velocity and 

 direction; then by summing for each such wind a large number of observa- 

 tions, the tidal-current may be considered as very nearly eliminated. 



In the present investigation the observations were tabulated with reference 

 to winds from a given direction divided in groups covering a range of wind 

 velocity of 10 miles. The results derived show that on the Pacific Coast at 

 a distance of from 4 to 10 miles from the land, winds from 10 to 70 miles per 

 hour will give rise to currents from ^ 4 of a knot to over a knot; and this current 

 will set, not in a direction of the wind, but in a direction of about 20° to the 

 right of the wind. This has an important bearing on navigation, since winds 

 blowing parallel to the coast or even away from the coast may give rise to 

 currents tending to set a vessel on shore. 



In the results presented for each of the light vessels the effect of fresh- water 

 run-off at the light vessels stationed off San Francisco, Columbia River and 



