Open main menu

Page:Popular Science Monthly Volume 19.djvu/130

This page has been validated.
120
THE POPULAR SCIENCE MONTHLY.

Report of the Commissioner of Education for 1878. Washington: Government Printing-Office. 1880. Pp. 730.

The office of the Commissioner of Education is a peculiar one. It has no authority, but depends wholly upon voluntary assistance for the collection of the information which it undertakes to digest and diffuse, and its recommendations, if it makes any, can pass only for what they are intrinsically worth. Its function, as the Commissioner well remarks, is that of "'a national clearing-house' of educational information, where what has been done is carefully recorded, and that which indicates the good or bad may be selected." That its work is more appreciated every year is shown by the steadily increasing number of its correspondents at home, who numbered 7,135 in 1878, and the extension of its connections abroad. The present volume contains full information, with all the details, on the condition of public and private education in the United States, arranged by States, and according to the grade and character of the institutions, and one of the most satisfactory accounts of the condition of education in foreign countries that the Commissioner has yet been able to present.

Photometric Researches. By William H. Pickering. Extracted from the Proceedings of the American Academy of Arts and Sciences. Cambridge, Massachusetts: University Press. 1881.

Very little is known with accuracy of any terrestrial high temperature, while estimations of that of the sun vary between the extreme limits of several million and two thousand degrees. In the researches to which this paper is devoted, Professor Pickering has endeavored to determine some of these temperatures by means of the amount of violet rays given off, these being the rays most abundant at the highest temperature. The exact relation between these factors is unknown, but, by assuming one which his experiments led him to regard as probable, Professor Pickering has been able to make out a table which does not differ widely from the most reliable determinations heretofore made. The lights of a candle, gas–flame, lime, magnesium, the electric arc, moonlight, and sunlight were each examined by means of a spectroscope and photometer, and the relative brilliancy of the red, yellow, green, and violet rays determined. The standard used was an Argand gas-flame with a small screen interposed, so that the light yielded was just ·67 candle-power, and a candle was found to be wholly unsatisfactory for the purpose. The relative intensities of these portions of the spectrum were in each of the lights as follows, that of the yellow rays being taken at 100: Candle, 73, 100, 104, 134; gas, 74, 100, 103, 125; lime, 59, 100, 113, 285; magnesium, 50, 100, 223, 1,129; electric light, 61, 100, 121, 735; moonlight, 87, 100, 155, 363; sunlight, 45, 100, 250, 2,971. The great preponderance of the violet rays in burning magnesium over those of any other artificial light clearly indicates a higher temperature, while by the same test that of the sun is much greater. The temperatures for all the lights measured are: Candle and gas, 1,200° C.; lime, 2,000° C., about that of melted platinum; electric arc, 3,500° C.; magnesium, 4,900° C.; sun, 22,000° C. This method of obtaining temperatures gives promise of being of great value, for, as pointed out by Professor Pickering, if the relation between increase of temperature and increase of violet rays were accurately determined, we could very readily determine the temperature of the heavenly bodies.

Studies of the Food of Birds, Insects, and Fishes, made at the Illinois State Laboratory of Natural History. Normal, Ill. Paper. Pp. 160.

The State Legislature of Illinois recently authorized an investigation of the food of the birds of the State, with especial reference to agriculture and horticulture, and a similar investigation of the food of fishes, with especial reference to fish-culture. The papers in this collection are the first results of the work. As the investigation proceeded it was found that, to be full, it must include a consideration of parts of the general subject of the reactions between groups of organisms and their surroundings, organic and inorganic. With this view the special papers are preceded by a more general one on "Some Interactions of Organisms." Papers are also given on "Insectivorous Coleoptera," and on "The Food of Predaceous Beetles."