Mat 14, 1920] 



SCIENCE 



491 



Pj = P3 = P (atmospheric pressure), 

 tii==0, v™^ F (coDEtant speed through tube), 

 and applying Bernoulli's principle 



P + h,dg = P + hMg + idV, 

 whence 



r'=2g{\ — lu) = 2gDA, 

 which expresses a simple interchange of po- 

 tential and kinetic energy, corresponding 

 strictly with the facts upon the assumption 

 that the operation is frictionless. 



It will be easy to express the reduced pres- 

 sure at the level A, inside the tube, by com- 

 paring two points at level A, one outside, the 

 other inside 



We have, outside 



side 



and thus 



p, = P v,= 0, 



h,' = \ v^' = Y, 



p/ + \'dg 4- MF^' = F -f h^dg, 

 p^' = P — idr', 



but 



idV' = dg(h, — h,); 

 therefore 



p^' — P — dgiK — h;}. 



We can now discuss the invariable refrain 

 or coda found in all the type treatments. It 

 appears to be based upon the assumption that 

 a liquid can not exist with a negative pres- 

 sure, or as sometimes expressed, under ten- 

 sion. This is hardly true; there is consider- 

 able experimental evidence to the contrary. 

 Let us make this assumption, however, and 

 limit the working height of the siphon to that 

 which makes the pressure zero at the highest 

 point. 



Comparing points C (at level B) and D we 

 have 



At 



Po^O, ro=F. 



At I? 



P2 = P, «2 = F. 



Ji,dg + idr' = P + h,dg + Jd^ ; 

 whence 



{K — }h)dg = P. 



Now h^ — h„ is the difference in level be- 

 tween D and B, which is thus shown to equal 

 the barometric height for the given liquid, in 



the assumed linaiting case. The ordinary 

 statement asserts that AB equals the baro- 

 metric height in the limiting case, the loss of 

 pressure at A inside the tube being over- 

 looked, and the concept being hydrostatic 

 rather than hydrokinetic. 



This discussion is not original in sub- 

 stance; see some good treatises on hydro- 

 dynamics. 



Harold C. Barker 



THE AMERICAN ASSOCIATION FOR 

 THE ADVANCEMENT OF SCIENCE 



SECTION E— GEOLOGY AND GEOGRAPHY 



The seventy-second meeting of Section E (Geol- 

 ogy and Geograiphy) of the American Association 

 for the Advancement of Science was held in the 

 Soldan High School 'buildiing in St. Louis, Mo., on 

 Decemlier 30 and 31. In the absence of Professor 

 Charles Kenneth Leith, the vice-president elect of 

 Section E, Dr. David White, chief geologist of the 

 XJ. S. Geological Survey, was voted chairman for 

 the St. Louis meeting, and presided. 



The address of the retiring vice-president, Dr. 

 David "White, upon the subject, "Geology as 

 Taught in the United States," was given on the 

 morning of December 31 in the main auditorium, 

 before a joint session of the Association of Amer- 

 ican Geographers, the Ameriican Meteorological So- 

 ciety, and Section E. This address will be printed 

 in full in SCIENCE. 



The vice-president of Section E for the coming 

 year will be elected by the executive committee at 

 its meeting in April. Dr. Nevin M. Fenneman, of 

 the University of Cincinnati, was elected member 

 of the council. 



The program which was so full that each session 

 overran the allotted time, comprised the following 

 papers : 



The origin of glauconite : W. A. Taer. Glaueo- 

 nite lis a hydrous silicate of iron and potash. The 

 composition is variable, but the amount of potash 

 rarely exceeds 8 per cent. The mineral is 

 amorphous, and is usually some shade of green. It 

 occurs as rounded grains and irregular areas in 

 dolomites, limestones, conglomerates, marls, sand- 

 stones and shales. It is found in the Cambrian 

 formations of Missouri, Olclahoma, Texas, South 

 Dakota and Wyoming, and in the Cretaceous and 

 Eocene formations along the Atlantic and Gulf 

 coasts. Geographically and geologically, glauconite 

 is associated with granites, usually being deposited 



