Page:Popular Science Monthly Volume 15.djvu/445

 W. Pike, of the island of Achill, Ireland, and was hatched in 1877 by a tame eagle. The eagle having laid three eggs, Mr. Pike took them away, substituting for them two goose-eggs, upon which the eagle sat, and in due time hatched two goslings. One of these died, and was torn up by the eagle to feed the survivor, who, to the great surprise of its foster-parent, refused to touch it or any other flesh-meat offered by the eagle. In course of time, however, the goose learned to eat flesh, and now the eagle always calls it by a sharp bark whenever there is any fresh meat in the cage. On hearing the call the goose hastens to the cage, and greedily swallows all the flesh and offal which the eagle gives it.

The King-Vulture.—A traveler in Colombia, André, confirms from personal observation the popular belief in that country that the urubu (or black vulture) dreads the king-vulture (Sarcoramphus papa), and slinks away when that monarch of the Cordilleras makes his appearance. On one occasion André saw the carcass of a cow covered with urubus which were greedily devouring it. Suddenly a black point appeared in the sky overhead. One of the urubus uttered a cry, and at once all the heads were raised to observe the enemy, who was coming ever nearer and nearer. In less than a minute the urubus had fled to a respectful distance, and the king, descending like a thunderbolt into the entrails of the carcass, began his meal with avidity. This operation took up half an hour, the urubus in the mean time standing around in a wide circle. They did not return to the carcass till after the king had risen majestically into the upper air.

The Size of Lightning-Rods.—In calculating the relative sectional areas of copper and iron lightning-rods, certain important factors are commonly overlooked, and thus of necessity incorrect results are obtained. The relation usually given, that an iron rod should have four times the sectional area of the copper rod, is based on the fact that copper conducts electricity six times as well as iron, while the melting-point of iron is about fifty per cent, higher than that of copper, and 6 divided by 1·5 is equal to 4. This simple treatment, as is pointed out by R. S. Brough, in the "Philosophical Magazine," is incomplete, because it neglects these factors: 1. The influence of the rise of temperature in increasing the electrical resistance of the metal; 2. The difference between the specific heats of the copper and iron; 3. The fact that the iron rod being made several times more massive than the copper one, it will require a proportionally greater quantity of heat to increase its temperature. Taking these considerations into account, Mr. Brough finds that the sectional area of an iron rod should be to the sectional area of a copper rod in the ratio of 8 to 3.

 

forty-ninth meeting of the British Association for the Advancement of Science will be held at Sheffield on Wednesday, August 20, 1879, under the presidency of Professor G. J. Allman, M.D., LL.D., F.R.S., L. & E.M.R.G.A., Pres. L. S. General Secretaries, Douglas Galton, P. S. Salator; Assistant Secretary, J. E. H. Gordon.

American Association for the Advancement of Science will assemble this year at Saratoga Springs, New York, on August 27th. Excursions to various points are contemplated, and the meeting promises to be a successful one. Officers of the Saratoga meeting: President, George F. Barker; Vice-President, Section A, S. P. Langley; Vice-President, Section B, J. W. Powell; chairman of Chemistry Sub-Section, Ira Remsen; chairman of Microscopy Sub-Section, Edward W. Morley.

French Association for the Advancement of Science will meet this year at Montpellier, on August 28th. The officers of the Association are: President, M. Bardoux; Vice-President, M. Krantz; General Secretary, Count de Saporta.

have received, but too late for mention in our June number, a circular announcing the second session of the Chesapeake Zoölogical Laboratory of Johns Hopkins University. The Laboratory is announced to be opened about June 20th, at Crisfield, on the Eastern Shore of Chesapeake Bay. One of the barges of the Maryland Fish Commission will be fitted up as a laboratory, and another barge will be used as a dormitory. As there will be room for only 