SECRETARY'S REPORT 75 



Dr. F. Belin Riggs is experimenting further with his design of an 

 electron probe microanalyzer, which makes possible a point-by-point 

 chemical analysis of polished surfaces of sectioned meteorites without 

 destroying the material. Combined with other metallurgical tech- 

 niques, it should throw light on the nature, history, and formation of 

 meteorites. His analyses so far show the need for a spectrometer, now 

 under construction, to scan X-ray wavelengths for the presence of 

 elements interfering with best results. 



Dr. John Wood has been studying the composition of chondrules to 

 determine whether his hypothesis, that they are hardened droplets of 

 liquid silicates which condensed from the vapor phase during the 

 origin of the solar system, is compatible with current solar theories. 

 Estimating temperatures and pressures in the models of Hoyle and 

 Cameron, and comparing them with those at which liquid silicates and 

 liquid metallic iron are stable, he concludes that conditions do obtain 

 in these models under which the droplets might condense. If, as he 

 has postulated, the chondrites should in fact prove to be original 

 planetesimals from which both planets and chrondrites accreted, re- 

 search into the birth and history of the planets can be greatly advanced. 



Important in this connection is Dr. Wood's almost completed analy- 

 sis of the compositional variation of about 50 chondrules separated 

 from the chondrite Bjurbole. For his quantitative arc spectrographic 

 study he has used equipment available at the Cabot Spectrographic 

 Laboratory at Massachusetts Institute of Technology. Dr. Wood has 

 also extended his investigations to the chondrite Renazzo, probably 

 a sample of quite primitive, unaltered planetary material, the detailed 

 mineralogy of which should reveal the nature of processes operating 

 during the origin of the planets. He is using the services of the Ad- 

 vanced Metals Corporation of Cambridge for his microchemical de- 

 terminations. From his examination of the probable metamorphism 

 of most chondrites, Dr. Wood is offering in a forthcoming paper a 

 hypothesis to explain the mineral peculiarities of unmetamorphosed 

 (e.g., Renazzo) chondrites. 



Dr. Pedro E. Zadunaislry's study of the definitive orbit of Comet 

 Halley 1910, to test current theories about forces perturbing the el- 

 liptic-orbit motion of a comet, has now achieved three written and 

 tested computer programs. Interpretation and reporting of results 

 will follow further development of these programs. 



Dr. Richard E. McCrosky, in collaboration with the Harvard Col- 

 lege Observatory, the United States Air Force, Lincoln Laboratory, 

 and NASA, has progressed in his attempt to reproduce meteor phe- 

 nomena by injecting into the upper atmosphere, at meteoric velocities, 

 bodies of known and sufficient size. His results are of critical im- 

 portance in calibrating the mass-luminosity and density scale of na- 

 tural meteors in the optical range. 



