350 



SCIENCE 



[N. S. Vol. XXVII. No. 687 



ptere of research and find expression among 

 the workers from all countries. The views of 

 contemporary workers on this subject were 

 explained and it was stated that while the 

 adherents of the theory of magmatic emana- 

 tions may go too far in some directions, this 

 theory has come to stay, and that it and no 

 other satisfactorily explains a great number 

 of ore deposits. 



The prevailing theoretical tendencies of the 

 present might be summed up as follows : We 

 unanimously agree in seeking the ultimate 

 source of the metals in the igneous rocks. 

 "We say that the rarer metals in concentrated 

 forms, dissolved in water, emanate from the 

 magmas during and after their eruption into 

 higher levels of the lithosphere, and that 

 minerals containing these metals are deposited 

 along the pathways of the waters. We assert 

 that atmospheric waters may search the con- 

 gealed rocks, abstract from them a part of the 

 small residues of the valuable metals, and de- 

 posit them along the channels. We say 

 further that metamorphism, when acting upon 

 these igneous rocks, is a potent factor in 

 favor of further concentration, aided by the 

 moisture contained in the rocks. 



We say finally that as erosion degrades the 

 volcanic mountains and their ore deposits, and 

 the fragments are carried down to form sedi- 

 mentary beds, the heavy native metals, such 

 as gold and platinum, are concentrated into 

 placers, and the baser metals are distributed 

 as salts of various kinds throughout the beds. 

 Atmospheric waters take up these particles 

 into solution, and, aided by the influence of 

 reducing substances as organic matter, con- 

 centrate them as deposits in congenial places. 



At the close of Mr. Lindgren's address the 

 fifteenth annual meeting of the society was 

 held for the purpose of electing officers, and 

 the following oiEeers were elected for the 

 ensuing year. 



President — Mr. Waldemar Lindgren. 



Vice-presidents — Mr. M. R. Campbell and Mr. 

 A. H. Brooks. 



Secretaries — Messrs. Ralph Arnold and Philip 

 S. Smith. 



Treasurer — Mr. Joseph A. Taflf. 



Members at Large of the Council — 0. A. Fisher, 



F. L. Hess, C. E. Siebeiithal, G. B. Riehardaon, 

 George H. Ashley. Fred E. Wright, 



Becretary 



DISCUSSION AND CORRESPONDENCE 



THE TEACHING OF MECHANICS 



To THE Editor of Science: It seems to me 

 high time for something to be done for the 

 teaching of the first principles and definitions 

 of mechanics in our schools. In the " Eeport 

 of the Committee of the Central Association 

 on Algebra in the Secondary Schools " which 

 has just reached me. I find the following : 



6. Momentum = velocity X weight. It is a 

 measure of the force with which one body strikes 

 another. 



The " clear and concise statements " of 

 physical laws which the committee recom- 

 mends should have the additional merit of a 

 reasonable degree of accuracy. 



Ernest W. Brown 



New Haven, Conn. 



adjustable burden baskets 

 To THE Editor of Science: Dr. William L. 

 Abbott has sent to the U. S. National Museum 

 five Dyak biirden baskets of an entirely new 

 type. They might be called " adjustable bur- 

 den baskets," since by means of lacings their 

 holding' capacity may be expanded or con- 

 tracted, like a shoe front. 



Three of the specimens have each a frame- 

 work of two U-shaped bows crossing on the 

 bottom; the others have each a four-sided 

 footing, incurved on the sides and pinched 

 in at the corners to fit the lower ends of the 

 four uprights that strengthen the body. All 

 of the specimens are left open, the wrapping 

 on the upper margin being continued down 

 the front opening and united at the " up-set," 

 or place where the bottom turns into the 

 body. Hence the two margins are joined 

 together in the examples with U-shaped 

 bows even to the center of the bottom. The 

 border consists of a small rattan stem, whose 

 close neat wrapping with a thin split of the 

 same material is, at intervals of an inch or 

 two, united with the warps on the sides and 

 to the twined weaving of the upper margins, 

 by mousings. 



