710 



SCIENCE. 



[N. S. Vol. XV. No. 383. 



formed and showed examples of various types 

 of caves. The cave fauna was discussed in 

 detail and compared with that of Europe. 

 With the exception of one salamander, related 

 to Proteus of Europe, and one crustacean the 

 species of cave animals were stated to be 

 related to, or obviously modified from existing 

 forms of the regions in which the caverns are 

 located. E. A. Lucas. 



PHILOSOPHICAL SOCIETY OF WASHINGTON. 



The 550th meeting was held March 29, 1902. 

 Mr. Marcus Baker discussed this geometrical 

 proposition: 'If one comer of a cube he cut 

 off by an oblique plane the sum of the squares 

 of the areas of the three faces adjacent to the 

 corner is equal to the square of the area of the 

 opposite side.' This can easily be proved 

 analytically; but as the relation requires four 

 dimensions, and no geometrical proof is 

 known, the speaker held the relation was 

 merely numerical. Professor Gore concurred 

 in this view. 



Mr. G. K. Gilbert presented the geophysical 

 problem of the pressure of a glacier on its bed 

 at a point below the surface of the sea, and the 

 contradictory solutions that had been given. 



The first regular paper was by Professor J. 

 H. Gore, on 'The Ambiguity of the Double 

 Sign' ± occurring in the extraction of roots. 

 He pointed out that ordinarily we determine 

 by experience which of these signs is the true 

 one in a specific ease; but in cases outside of 

 experience we have no criterion to guide our 

 judgment. This was illustrated by various 

 examples. 



Mr. C. K Wead then spoke on 'The Theory 

 of some Peculiar Musical Instruments in the 

 National Museum.' The instruments included 

 the globular four-hole whistles from Costa Eica, 

 figured by Messrs. Wilson and TJpham in the 

 'Museum Eeport' for 1896, and similar less 

 perfect whistles in other museums, and various 

 kinds of primitive flutes. The scales produced 

 on these are only by accident diatonic, and the 

 laws cleanly are applicable to the instrument, 

 not to the notes. A new generic principle of 

 primitive scale-making was enunciated, and 

 various specific forms of the principle. The 

 fuller statement of these laws will soon appear 



in the 'Eeport of the U. S. National Museum' 

 for 1900. 



Mr. IJpham then exhibited several of the 

 instruments and performed on them. The type 

 whistle or resonator gave very closely the 

 notes F (690 d. v.). A, 0, D, E. 



The 551st regular meeting was held April 

 12, 1902. 



The election to membership of Mr. S. W. 

 Stratton, of the Bureau of Standards, and Mr. 

 W. J. Spillman, of the Department of Agricul- 

 ture, was announced. 



The paper of the evening was on 'Liquid 

 Air,' by Mr. G. A. Bobrick, superintendent of 

 the only establishment furnishing liquid air 

 commercially. The consumption is now about 

 150 gallons per week; the carriers are so 

 well insulated that a gallon will not wholly 

 evaporate under about a month, and recent 

 improvements have largely diminished the loss 

 from their fragility. The well-known experi- 

 ments were fragility to show the effects of 

 intense cold, —312° F., on various kinds of 

 bodies, and the use of the liquid for explosives 

 and to promote combustion. Apparatus was 

 exhibited showing the production of the lime 

 light by gas and liquid air. The history of the 

 liquefaction of gases during nearly a century 

 was given, with brief description of the three 

 processes used; the bent tube (Davy), the cas- 

 cade or closed double cycle (as by Pictet), and 

 the self-intensive or regenerative systems. 

 This last in practice yields a pound of liquid 

 air per pound of coal used. 



The speaker finds this an ideal source of 

 power, where the expense is not prohibitive: 

 seventeen gallons drives his automobile fifty to 

 sixty miles. While it will never be used for 

 stationary engines, it will be useful for sub- 

 marine and aerial navigation. It is used in 

 manufacturing chemicals and food extracts, 

 and has already important medical uses. 



Charles K. Wead, 

 Secretary. 



the geological society op WASHINGTON. 



At the meeting of the Society on April 9, 

 Mr. S. F. Emmons read parts of an address 

 delivered by Clarence King in June, 1877, on 

 the thirty-first anniversary of the Sheffield 



