POPULAR SCIENCE MONTHLY.
more simple and regular, says Captain W. J. L. Wharton, than in the British Isles, in remarkable contrast to the opposite American coast, where it is very complicated. The minor tides, which in most parts of the world considerably affect the volume of the whole, are in Great Britain comparatively insignificant; why, is not yet explained. Some curious interference phenomena originating in the meeting of tidal waves from opposite directions, or in rebounds from the coasts, have been observed in the British Isles. The tidal range of about fifteen feet on the western part of the southern coast of England diminishes as we go eastward to one of six feet near Poole, then increases to Hastings, where it is twenty-four feet, and then, farther east, gradually diminishes. This is due to reflection from the French shores, which brings waves that here re-enforce, there reduce, the main wave, according to details so complex that they have not yet been studied out. Variations in the mean range of tides on many coasts may be accounted for as resulting from such reflections, which may come from longer distances and be more numerous than we are now aware of.
Toads at Dinner.—The toad does not take dead or motionless food. Only living and moving insects, centipeds, etc., are devoured, while worms or other larvæ disturbed by their hopping are safe so long as they remain curled up; but as soon as they move they are captured. The toad's tongue, its only organ for seizing food, is soft, extensile, attached in front but free behind, and is covered with a glutinous substance that adheres firmly to the food seized. So rapid is the motion of this weapon that a careful watch is necessary in order to see the animal feed. At night, soon after sunset or even before on cool evenings, the toad emerges from its shelter and slowly hops about in search of food. Something of a regular beat is covered by these animals, whose sense of locality is strong. In the country this beat includes forage along the roadside, into gardens and cultivated fields, and wherever insect food is abundant and grass or other thick herbage does not interfere with getting about. In cities and suburban villages the lawns, walks, and spots beneath the electric lamps are favorite hunting grounds. At Amherst, Mass., Mr. A. H. Kirkland, from whose paper we derive these observations, once counted eight large, well-fed toads seated under an arc light and actively engaged in devouring the insects which, deprived of wings, fell from the lamp above. At Maiden, Mass., a colony of about half a dozen toads sally forth on summer evenings from under the piazza of a citizen's house, go down the walk, cross the street, and take up their stations under the arc lamp, where they feed upon the fallen insects till the current is turned off, when they return to their accustomed shelter.
Unexplored Regions in Asia.—In the coming century there will be abundance of work for explorers in Asia, said Dr. J. Scott Keltie in the British Association, and plenty of material to occupy attention. They lie in two separate regions. In southern and central Arabia there are tracts which are entirely unexplored. These regions are probably a sandy desert. At the same time they are, in the south at least, fringed by a border of mountains, whose slopes are capable of rich cultivation, and whose summits the late Mr. Theodore Bent found to be covered with snow. If any traveler cared to face the difficulties, physical, political, and religious, which would probably be met with, he might be able to tell the world a surprising story. Another region in Asia where real pioneer work still remains to be done is Tibet and the mountainous districts bordering it on the north and east. Lines of exploration have in recent years been run across Tibet by Russian expeditions like that of Prejevalsky, by Rockhill, Prince Henry of Orleans, Bonvalot, Bower, Littledale, Wellby, and Malcolm. From the results obtained by these explorers we have formed a fair idea of this, the most extensive, the highest, and the most inhospitable plateau in the world The forbidden city of Lassa is at present the goal of several adventurers, although as a matter of fact we can not have much to learn in addition to what has been revealed in the narrative of the native Indian traveler, Chandra Das. The magnificent mountain region to the north and east of Tibet furnishes a splendid field for the enterprising explorer. Then there are the series of parallel mountain chains southeast of Tibet through which the upper waters