554 proceedings: the Washington academy of sciences 



the streets, the kinds of trees and other details. As abundantly demon- 

 strated, the subject of nematodes, in addition to its unusual scientific 

 interest, is also of great economic importance. 



The 101st meeting of the Academy was held Thursday, April 1, 

 1915, at 4.45 p.m., in the Auditorium of the New National Museum. 

 Dr. Charles E. Munroe, Dean of Graduate Studies, George Wash- 

 ington University, gave an illustrated lecture on High explosives and 

 their effects. The nature of an explosion was made clear by reference 

 to combustion, and the way in which it is facilitated by subdivision of 

 the combustible. The history of each of the more important explo- 

 sives was given. Its chemical structure, the process of its manufac- 

 ture, and its uses, both in civil operations and in warfare, were all fully 

 explained. In several cases the original ingredients and the final 

 compound were all shown. Many surprising results produced by high 

 explosives were illustrated by lantern slides, and a remarkable series 

 of iron plates was exhibited on which high explosives had left impressions 

 of leaves, laces, and other relatively soft and delicate objects. 



The 102d meeting of the Academy was held Thursday, April 8, 

 1915, at 4.45 p.m., in the Auditorium of the New National Museum. 

 Mr. W. D. Hunter, of the Bureau of Entomology, gave a lecture on 

 hisects and their relation to disease. It was shown that with the dis- 

 covery of Pasteur the empirical age of medicine began gradually to 

 be replaced by an exact knowledge of the cause of disease and an under- 

 standing, in many cases, of how to prevent it. A further great advance 

 was made when it was clearly recognized that of several of the more 

 formidable diseases, such as malaria, yellow fever, bubonic plague, 

 sleeping sickness, and typhus fever, each depends not only for its trans- 

 mission but even for its existence upon one or another species of insects; 

 while still others, of which diphtheria and typhoid fever are typical 

 examples, are similarly spread from place to place. Hence the relation 

 of insects to disease is of the greatest importance. Sanitation, the pre- 

 vention of epidemics, and the reduction of disease to a minimum is, 

 therefore, a biological rather than a medical problem. 



The 103d meeting of the Academy was held Thursday, April 15, 

 1915, at 8.30 p.m., in the Auditorium of the New National Museum. 

 Dr. R. S. Woodward, President of the Carnegie Institution, gave a 

 lecture on The Earth. The dimensions and mass of the Earth were given 

 in terms of ordinary familiar units and, therefore, for the most part in 

 exceedingly large numbers. The Earth was conveniently divided 

 into four distinct but very unequal parts, namely: The atmosphere, 

 concerning whose upper or outer portion but little is known; the hy- 

 drosphere, essentially the oceans, which in many respects is well known; 

 the Hthosphere, or rocky crust, also comparatively well known; and the 

 centrosphere, or all that part of the earth below its rocky shell. In 

 comparison with the other parts almost nothing is known of the 

 centrosphere. 



W. J. Humphreys, Recording Secretary. 



