PHYSICS.
The Proceedings of the Paris Congress of 1900 on Methods of Testing Materials' have just appeared in three large folio volumes. The first article by M. Ricour has for its title 'The Molecular Constitution of Matter' but is largely devoted to the discussion of the laws of attraction and to the properties of the ether of space. This ether he imagines to be a sphere whose radius, though great, may perhaps be ultimately found. The distance of our sun from the center of this sphere of ether he finds to be such that light would require 140,000 years to traverse it. The density of the ether he finds to be such that a mass equal in size to our earth would be equal to about one kilogram. While much of the work rests upon hypotheses, the article of Ricour is interesting as showing how the engineer as well as the physicist finally comes to the ether as the ultimate source of all energy. If the ether is really a limited sphere, as he supposes, the surface of that sphere forms an absolute limit to our knowledge; for should other spheres of ether exist no waves can pass across the empty spaces that separate them from that sphere which contains our universe.
MOSQUITOES AND MALARIA.
Dr. Leland O. Howard, the entomologist to the United States Department of Agriculture, has just given us a little book on 'Mosquitoes' (McClure, Phillips & Co.) that is peculiarly well timed and important. Dr. Howard has studied his subject for many years; primarily, in the past, to devise methods for the local control of an annoying pest; but recently, since the relation of some of the genera to the spread of malarial and other febrile diseases has been established, to ascertain their peculiarities of habit and development.
Public interest in the newspaper and magazine accounts has been so marked that a book like this which gives in concise form and with scientific accuracy just what is known of the relation between disease and insects must be especially useful to correct the misinformation gaining currency among the general public. Dr. Howard gives us in detail the life history of our commonest species; both Culex, which is an annoyance merely, and Anopheles, which is the intermediate host for the organism producing malarial diseases in man. The breeding places of each are discussed and the measures which may be adopted to do away with them. A very complete account is given of the experiments which link the Stegomyia fasciata with yellow fever, and a brief statement shows the relation between Culex ciliaris and Filariasis. A chapter on classification shows fairly well what is known of our American species and gives some indication of what yet remains to be learned.
