510 



SCIENCE. 



[N. S. Vol. XI. No. 274. 



On the conclusion of Professor Geddes' ad- 

 dress, Hon. D. R. Francis, on the call of the 

 President, spoke briefly on the subject pre- 

 sented by Professor Geddes, expressing a warm 

 interest in the work of the Association, the co- 

 operation of which with the Louisiana Pur- 

 chase Exposition being planned for St. Louis, 

 a few years hence, is hoped for. 



A paper by Dr. G. A. Miller, ' On the primi- 

 tive substitution groups of degree ten,' was 

 presented bj' title. 



Professor J. L. Van Ornum, late of the 

 United States Engineer Corps, spoke interest- 

 ingly on ' The sanitary cleaning of a city, as 

 exemplified by Cienfuegos, Cuba,' explaining 

 the conditions found by the United States 

 Army on taking possession of that city, and 

 the thoroughness with which the streets, court 

 yards and cesspools were cleansed by the Engi- 

 neer Corps, which also charged itself with the 

 betterment of the city water supply. A diagram 

 which the speaker had prepared showed that 

 in addition to a very marked lowering of the 

 death rate which attended the supply of an 

 abundance of wholesome food, on the occupa- 

 tion of Cienfuegos, there had been a decrease 

 of considerably over fifty per cent, in the 

 weekly death rate, directly attributable to the 

 Banitary cleansing of the city ; and he further 

 stated that since this work had been done, yel- 

 low fever, which before that time had been 

 endemic in Cienfuegos, had been absent from 

 the city. 



Five persons were elected to active member- 

 sh p in the Academy. 



William Teelease, 

 Recording Secretary. 



DISCUSSION AND COBBESPONDEiVCE. 



'floating SAND.' 'FLOATING STONES.' 



In the American Geologist for January, 1896 

 (Vol. XVII, pp. 29-37) I published an arti- 

 cle on ' Floating Sand : an Unusual Mode of 

 Eiver Transportation ' in which I gave a de- 

 tailed account of that phenomenon as seen by 

 me during the preceding August on the Llano 

 river, a tributary of the Colorado, at Bessemer, 

 a station on the Austin and Northwestern Rail- 

 road, 94 miles from Austin, Texas. I further 



gave an account of numerous experiments per- 

 formed for the purpose of ascertaining how sand 

 may be floated, what sand will float, and why 

 sand will float. No less than fourteen different 

 sands were examined some of which were from 

 widely separated localities, as, for instance, the 

 coast of Long Island and that of Lake Michigan, 

 at Chicago ; from the friable sandstone at Alum 

 Bay, Isle of Wight, and the Lower Carbonif- 

 erous at Pea Ridge, Arkansas. At the time of 

 writing, I may add, the only account of floating 

 sand known to me was in a brief article ' On 

 a Peculiar Method of Sand-Transportation by 

 Rivers ' published by Mr. James 0. Graham in 

 the American Journal of Science, III, Vol. XL, 

 p. 470 (December, 1890) and this I had failed to 

 notice until I had begun my investigations. 



Without going into the details of my paper 

 further at this point, I will enumerate the con- 

 clusions reached which were as follows : 



" 1. That sand grains will float in perfectly still 

 water for an indefinite time. 



" 2. That the grains which float are not necessarily 

 siliceous. That flakes of mica, fragments of marble, 

 bituminous shale, etc., also float and that some of 

 them, the marble and the bituminoua shale, for ex- 

 ample, are unusually buoyant. 



" 3. That the property of floating is not confined 

 to the sand of any particular locality, but depends to 

 a considerable extent upon the angularity, i. «., the 

 shape of the grains. 



"4. Tliat whether sand will float or not depends, 

 also, upon the mode of launching. Whether it be by 

 ripple waves, as stated by Mr. Graham, or by under- 

 mining, it must be gently done, for should the grains 

 be plunged into the water with sufficient force to 

 completely immerse them they will immediately 

 sink. 



"5. That the natural conditions necessary to the 

 floating of sand in ri%-ers are somewhat unusual, de- 

 pending, in the case of the Llano, upon a flood with- 

 out local rains and, in that of the Connecticut, upon 

 the manner in which certain waves strike a sand-bar. 

 It is quite possible, however, that floating sand is 

 much more common than is ordinarily supposed. 



"6. That the physical explanation of the problem 

 is complex rather than simple, and at best unsat- 

 isfactory in several important particulars, and that 

 with the advance of molecular physics we may hope 

 for a better understanding of what we now, for con- 

 venience, term ' superficial viscosity ' and ' capillary 

 attraction.' " 



