SCIENCE 



Friday, Januaby 25, 1918 



CONTENTS 

 The American Association for the Advance- 

 ment of Science: — 



Some Needs of Engineering: Professor 

 Henry M. Howe 75 



Food-home Infections: Professor Edwin 



O. Jordan 80 



Scientific Events: — 



The General Medical Board of the Council 

 of National Defense; United States Dye- 

 stuffs; The Board of Natural Resources and 

 Conservation of the State of Illinois 86 



Scientific Notes and News 90 



University and Educational News 92 



Disc^ission and Correspondence: — 



A Suggestion to Morphologists and Others: 

 Dr. L. O. Howard 93 



Scientific Bools: — 

 Jeffrey's The Anatomy of Woody Plants: 

 D. H. S 94 



Special Articles: — 



On the Series of the Ultra-violet Fluores- 

 cence of Sodium Vapor: Dr. H. L. Howes. 96 



The American Association for the Advance- 

 ment of Science: — 

 Section G — Botany: Dr. A. F. Blakeslee. 99 



The American Mathematical Society: Pro- 

 fessor F. X. Cole 100 



MSS. ioiended for publication and book^, etc.. intended for 

 ie\'iew ehoulo b« sent to The Editor of Bdeneet GarrisoD-on- 

 Hudaon, N. V. 



SOME NEEDS OF ENGINEERINGi 

 Let me remind you that the practise of 

 our art is still empii'ical in that most funda- 

 mental matter, the strength of the materials 

 which we use, their ability to resist the 

 stresses to which we expose them. It will 

 suffice to touch on two phases of this mat- 

 ter, that our reception tests are quiescent, 

 though in manj' cases thej' should be ki- 

 netic, and that thej' do not determine the 

 true resistance of the material even to rela- 

 tivel.y quiescent stress, as it is applied in 

 many important services. Let us consider 

 these two in series. 



It should be au axiom that reception 

 tests should represent the most trying serv- 

 ice stresses, which in many important cases 

 are kinetic, arising from impact, shock or 

 very rapid application of stress. This is 

 true of gun hoops, shells, rails, tires, axles, 

 and many parts of motor cars, and of agri- 

 cultural and other important classes of ma- 

 chinery. The fitness of such materials for 

 enduring these kinetic stresses should be 

 determined primarilj- by means of impact 

 tests. For each service the severity of this 

 impact should represent the greatest and 

 most rapidly applied stress which is to be 

 expected. 



What would you say to using a hydraulic 

 press to determine the ballistic resistance of 

 armor plate or the resistance of a safe to a 

 burglar's sledge? Yet it is only in de- 

 gree that our present practise is less ra- 

 tional than this, and it is only because fa- 



1 Address of the Vice-president and Chairman of 

 Section G, of the American Association for the Ad- 

 vancement of Science, Pittsburgh, December 28, 

 1917. 



