Page:Popular Science Monthly Volume 13.djvu/267

This page has been validated.

and the second is, that it should be so varied as to afford at the same time pleasurable mental excitement or occupation. In both of these points the theory of the "health-lift" is faulty. It calls into action almost exclusively the extensor muscles of the lower extremities, and the erection of the spine with the associate dorsal groups. As far as the upper extremities are concerned, the only muscles called into activity are the flexors of the fingers; those of the arm and shoulder are simply put on the stretch, an operation which, without corresponding contraction, weakens rather than strengthens muscular fibre. At the same time, the ligaments of the joints are violently stretched, which must tend to diminish the completeness of the apposition of the joint-surfaces, and thus diminish precision and rapidity of motion. As regards variety and occupation for the mind, the "health-lift" confessedly possesses no such quality. Finally, the "health-lift" is not a safe mode of exercise. It tends to produce apoplexy, rupture of blood-vessels, hernia, and other serious evils. The author concludes with these words: "Concentrated exercise is as unsatisfying to the muscle as is concentrated nourishment to the stomach. The latter demands bulk in its contents, the former a certain duration in its period of activity."



The third session of the Bowdoin College Summer School of Science will open on July 15th, in the Cleveland Lecture-Room, and will continue for six weeks. Three courses will be given, viz., Chemistry, by F. C. Robinson, Instructor in Chemistry in the college; Mineralogy, by H. Carmichael, Professor of Chemistry; and Zoology, by L. A. Lee, Instructor in Natural History. This school is designed to give to teachers, gradates of colleges, and others, of both sexes, a practical acquaintance with science.

Dr. George M. Beard is collecting materials for a work on "writers' cramp," and other diseases of an analogous nature, as the cramp of artists, pianists, violinists, telegraphers, etc. He invites those who possess any information regarding these subjects to communicate the same to him. He will supply blanks on application. His address is "41 West Twenty-ninth Street, New York."

Captain Lunginers, of the Danish vessel Lutterfeld, reports that while off the coast of Terra del Fuego, latitude 65° 15' 10" south, longitude 15° 12' 10" west, at 3.30 a. m. of December 10, 1876, the man on the lookout espied at no great distance a considerable mass of land rising above the surface of the water in the shape of a hill about thirty metres high. As the charts had no mention of an island in that place, the captain resolved to lay-to till morning so as to investigate the discovery more fully. The next day at 5.30 a. m. the island appeared to be much smaller, but he went to visit it with a boat's crew. The island was found to be spherical in shape, its sides pretty steep. One of the sailors sprang ashore, but he had to return to the boat quickly, for the ground was intolerably hot. The island continued to sink, and at 8 a. m. it was no more to be seen; and one hour later the vessel passed over the place where it had stood.

From a series of observations made by Dr. Jarvis Wight, of Brooklyn, it appears that in at least seventy-five cases out of every hundred the lower limbs of human subjects are of unequal length; nor does this difference exist in the total length of the leg alone, but also in the length of the several long bones which constitute its skeleton. The inequality varies from one-eighth of an inch to one inch, the average being one-fourth.

Prof. Cope, it is stated in the American Naturalist, has received from Oregon a collection of fossils from a Pliocene lake-bed, including, with others, Elephas primigenius, Equus occidentalis, and many other extinct species. But a circumstance of uncommon importance is that, in the same deposit in which these fossils were found, occur numerous flakes of obsidian, with arrow and spear heads of the same. All were lying mingled together on the surface of a bed of clay, which was covered by a deposit of volcanic sand and ashes, of from fifteen to twenty feet in depth.

According to Prof. F. J. Burrill, of the Illinois Industrial University, the catalpa possesses great advantages as a timber-tree, being the cheapest and easiest grown of all our forest-trees, native or introduced, and also the most rapid in its growth. On the same ground it has outgrown the white or American elm, white-ash, European larch, Osage-orange, black-walnut, etc. It is not attacked by insects, and is free from disease. A board sawed from a catalpa-log, which had lain on the ground for one hundred years, was found to be perfectly sound and strong, and susceptible of a fair polish.

Julius Robert Mayer, who shared with Joule the honor of working out to a demonstration the mechanical theory of heat, died