Page:Popular Science Monthly Volume 12.djvu/396

382 rhinoceros in the Regent Park Zoölogical Garden do not suffer even in very cold weather; and that in the isle of Saghalien, to the north of Japan, the reindeer is preyed upon by the tiger, which crosses the ice in pursuit of its victim. Hence it follows that mammals are not good indicators of temperature. Mr. Tiddeman rested his argument for man's antiquity in Britain on the occurrence of a (supposed) human fibula and two hacked bones of goats in deposits older than the post-glacial. But Prof. Busk objected that the "fibula" was probably ursine, and, at all events, that it was altogether too insignificant a fragment on which to base any far-reaching conclusion. The goat-bones, hacked as if by the hand of man, were found in Victoria Cave, at the depth of fifteen and twenty-five feet respectively. But it was urged that these bones really belonged to a superficial stratum, and had fallen down to a lower level while the work of excavation was going on. But, even supposing them to belong to the levels from which they were taken, these bones are not decisive as to the age of the deposit in which they were found—a matter which is still in dispute. Arguments pro and contra were advanced by sundry members of the Institute, and the various evidences of the antiquity of man were considered in the light of geology, anatomy, the science of language, and paleontology. But no positive result was reached one way or the other; nevertheless, the conference was not without fruit, inasmuch as it has done much to remove misapprehensions, and to indicate the proper lines of research.

Electricity in War.—Mr. H. Baden Pritchard, in one of his communications to Nature on scientific principles involved in the art of war, gives a sketch of the employment of electricity in military operations. He says that the employment of electricity for exploding charges of powder was suggested by Franklin and Priestley; only very recently, however, have we been in a position to make proper use of this valuable agent as a means of firing charges at a distance. One of the first applications made of the subtile fluid was in the removal of the wreck of the Royal George at Spithead, nearly fifty years ago, when the explosion of the charges was brought about by what is termed a wire fuse, a short piece of platinum thread stretched between two copper wires. The platinum bridge, having less conducting power than the copper wires, presents a considerable resistance to any current of electricity that passes, and so becomes heated sufficiently to ignite gunpowder. "But for many purposes," remarks Mr. Baden Pritchard, "the wire fuse is ill adapted to the military and naval services. A voltaic battery is necessary to evolve the low-tension electricity required to yield sufficient resistance and heat, and such a battery made up of metal plates, and involving the use of acids, is a cumbersome apparatus. In 1853 Colonel Verdu, of the Spanish army, with the aid of a Ruhmkorff coil, succeeded in firing half a dozen charges simultaneously. Wheatstone and Abel followed in Verdu's footsteps, and while the former directed his attention to the construction of a portable frictional apparatus, the latter busied himself in the preparation of a fuse inclosing a compound more easily explosible than gunpowder—a fuse which still holds an important place among warlike stores."

Alternation of Seasons and Tree-Growth.—The fact that the exogenous plants of the preglacial epoch show concentric growth-rings has been by many writers regarded as proof positive that in these times the earth's axis must have been inclined as at present, and that there must have been then, even as now, alternating seasons. But is alternation of seasons necessary to the formation of rings?

This question is considered by Dr. C. B. Warring, in a paper read before the New York Academy of Sciences, an extract from which has appeared in the American Journal of Science and Arts. The problem might be solved experimentally, says Dr. Warring, if we could secure for plants a uniform temperature throughout the year. The nearest approach to such a condition in this latitude is found in greenhouses. Exogenous plants so placed, e. g., the orange and lemon, form growth-rings as regularly as do forest-trees. The author has found it difficult to obtain any information as to the formation of these annual markings in exogenous plants growing in tropical regions.