PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON 



The 765th meeting was held on January 8, 1916, at the Cosmos 

 Club. President Briggs in the chair, 50 persons present. The min- 

 utes of the 763d meeting were read in abstract and approved. 



Mr. H. N. Heck presented by invitation a communication entitled, 

 Detailed submarine relief, a practical method of development. The 

 amount of detail required for submarine relief depends upon whether 

 the point of view is scientific or utilitarian. The standard methods of 

 obtaining knowledge of submarine relief were described and the reason 

 given why these are insufficient in manj r parts of the earth. The de- 

 velopment of the wire-drag method was described and that method 

 mathematically defined. The importance of geological accidents in sub- 

 marine relief was emphasized and two forms of especial importance 

 pointed out. Slides were shown to illustrate cases where submarine 

 relief agrees closely with the adjacent land forms and also to show, by 

 examples selected from all parts of the United States, Alaska, and else- 

 where, where there is marked disagreement, or forms entirety unex- 

 pected. Two ways were indicated in which geology can assist in de- 

 termining where the wire-drag method must be applied. The question 

 is open whether it is possible to predict from available geological in- 

 formation the existence or absence of certain forms of submarine relief . 

 The effect of submarine relief on the three principal motions of the sea 

 was briefly discussed. 



Discussion: Mr. Wright referred to dangers from hidden rocks ex- 

 perienced during geological expeditions in Alaskan waters. Mr. 

 Hazard asked how often it was necessary to change the height of the 

 drag. Mr. Sosman called attention to the recent discovery of a pin- 

 nacle of rock in the Liverpool Channel. Mr. Heck stated that it was 

 sometimes necessary to change the height of drag every 20 minutes. 

 The Chair expressed to Mr. Heck the thanks of the Society for his 

 very interesting communication. 



Mr. A. L. Thuras presented a paper entitled, A method of deter- 

 mining densities at sea and its use in locating ocean currents. A new 

 method of ocean-density measurement particularly adapted to sea 

 conditions was briefly discussed. The temperature of the water 

 sample was varied until its density was just equal to that of a glass 

 "bobbin." A calibration curve was shown giving the density of the 

 sample at 15°C. in terms of the equilibrium temperature. The 

 accuracy attained was greater than 0.008 per cent. A continuous 



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