SECRETARY'S REPORT 163 



able to study. Thus a long-standing objective has been met, and major 

 results from the operation of the improved network are imminent. 

 Using data selected from that obtained over the past several years, 

 Drs. Gerald S. Hawkins and Kichard B. Southworth have examined 

 the physical characteristics of the small radio meteors ; they find that 

 the majority of the faint radio meteors show total fragmentation. 

 The decrease in average velocity as the size of the bodies decreases, 

 originally reported by Drs. Hawkins, Southworth, and B. A. Lind- 

 blad, was studied further by Kemieth Baker.^ 



The relationship between the flux of meteors incident on the earth 

 and the observed rate of radio meteors has been determined by Dr. 

 W. G. Elford * in terms of (1) the distribution law as a function of 

 magnitude; (2) the density of meteor radiants over the celestial 

 sphere; (3) the parameters of the radio equipment; and (4) a simple 

 form for the ionized trail. The theory has been applied to the Har- 

 vard-Smithsonian Radio Meteor system at Havana, Illinois, and an 

 estimate has been made of the average flux over the earth of meteors 

 of magnitude ^ + 12. A provisional value of 80 km"%r"^ has been 

 obtained. The analysis is being extended to determine the relative 

 density of meteor radiants over the celestial sphere.* 



A new analysis of 413 precisely reduced meteors photographed some 

 years ago with the Super-Schmidt cameras has been made by Dr. 

 Jacchia, Dr. Franco Verniani, and Robert Briggs.^ Several physical 

 characteristics of meteor bodies, together with their interdependences, 

 have been determined more accurately than has hitherto been possible. 



Dr. Verniani's investigations of the luminous and ionizing efficiencies 

 of meteors have been completed. These two quantities are essential 

 for the determination of meteor masses and densities. The photo- 

 graphic luminous efficiency xp, measured with respect to kinetic energy, 

 has been rederived from Super-Schmidt photographic data, taking 

 fragmentation into account. The dependence of rp on the meteor 

 velocity v is found to take the form Tp'-"y". The exponent n turns out 

 to be 1.0d=0.15 for both faint and bright photographic meteors. The 

 present evaluation of Tp has also allowed the determination of the 

 ionizing efficiency Tq. Drs. Verniani and Hawkins * have f omid Tq'^v^. 

 The comparison of the rates of photographic and radio meteors of 

 about the same magnitude confirms this relation. 



The Observatory has established a field operation to observe the 

 luminosity and ionization produced by artificial meteors fired from 

 rockets launched at Wallops Island, Virginia.^ The Observatory now 

 operates two Super-Schmidt cameras for this program. A third 

 camera site will be built, and a prism will be added to an additional 

 Super- Sclunidt at the Wallops Island site. Four radar-receiving 



See footnotes, p. 177. 

 766-746 — 65 12 



