THE POPULAR SCIENCE MONTHLY.
that do best at high altitudes are those of simple phthisis, in patients who are free from cardiac, renal, or rheumatic complications, and who exhibit a torpid reaction to the disease.
Increasing the Tractive Power of Locomotives—Patents were granted in March to Elias E. Rics and Albert H. Henderson for methods and apparatus for increasing the tractive power of locomotives and other self-propelled rail vehicles. This is accomplished by increasing, by means of electricity, the frictional adhesion between the driving wheels and the rails. The apparatus consists of a dynamo-electric machine on the locomotive, from which a current of electricity passes through a converter, and thence through the driving-wheels in succession and that portion of the rails between them. Further, the current, which is of great volume and small motive force, is said to cause enough heat at the point of contact to vaporize at once any moisture on the rails, thus overcoming the slipperiness caused by snow and sleet. The inventors claim that, by their plan, the tractive power can be nearly doubled without increasing the weight of the locomotive, that a 40-per-cent grade can be more easily surmounted than a 7-percent one under the old system, that trains can be stopped and started much more quickly than at present, and that the friction obtained is cheaper than sanding, without its consequent wear.
An Exhibition of Insects.—An exhibition of useful and injurious insects was held in Paris a short time ago, at which five hundred entries of objects were made. Great pains were taken to awaken interest in it. Prizes were offered to school-children for the best compositions on their visits to it. Conferences were held in the rooms on questions relating to the study of insects. Medals were offered to rural teachers who sent collections gathered by themselves or their pupils. Booksellers offered books to those who sent the best collections and the best papers on entomology. Anatomical preparations were shown by Dr. Ozouf representing the organization of the silk-worm in its several states and of May-bugs; silks from Tonkin and Senegal; oak silk-worms raised in the open air which furnish a silk identical with the Chinese pongee; living ant-hills collected by M. Morel, a journeyman painter; ant-lions which had excavated their dens in the sand as if they had been in the woods; batrachians, lizards, adders, aquatic insects, wasps building and repairing their nests, bee-hives with windows through which the bees could be seen at their work; wasps' nests from Senegal, remarkable for their excessive hardness; gall-nuts of various kinds, and collections from several countries, with illustrations of various features of insect life and economy.
Construction of Mythologies.—Closely connected as mythology and folk-lore are shown to have been, says Mr. J. A. Farrer, it is difficult or impossible to say in any given case whether the superstition is derived from the myth or the myth from the superstition. The usual method of interpretation deduces superstition from mythology, making the latter the primary starting-point. But it is often quite as likely that the custom was there first, and that the myth made use of already existing customs; for instance, that the horse figured conspicuously in legend because it had long been an object of worship or superstition, is as likely as that it became an object of worship or superstition because it figured so conspicuously in legend. The horse is thickly set in folk-lore. In parts of Germany a horse's head may still be seen over the doors of cattle-stalls or about the houses—a custom which survives among ourselves in the luck attaching to a horse's hoof. This, perhaps, dates from the custom of our ancestors, mentioned by Tacitus, of keeping white horses in sacred groves at the public expense and idle, and forecasting the future from their neighings. A horse's neighing always presaged victory to a warrior, as his silence presaged defeat, and the French anticipated disaster at Agincourt from the fact of their horses not neighing on the eve of the battle. A horse's hoof under a child's pillow is supposed to be a preventive from convulsions, a horse's teeth are a safeguard against toothache, and houses at which they shy are threatened with calamity. There is no reason to look for any more abstruse explanation for the part which animals, birds, fishes,