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ing. In this connection, the author points out another error found in many text-books, namely that the oblique course of the winds is due to a lagging behind, as they move from regions of less to those of greater rotary velocity, and, therefore, that winds traveling due east would not be deflected at all. As was clearly shown by Ferrel, many years ago, both the explanation and its corollary are wrong, although they have appeared in many text-books, even of recent date.

Following the discussion of a competent theory for the general circulation of the winds, there is given a systematic account of the different members of the circulation, and a classification of winds according to cause into (1) planetary, (2) terrestrial, (3) continental, (4) land and sea breezes, (5) mountain and valley breezes, (6) cyclones and other storms, (7) eclipse winds, (8) landslide and avalanche blasts, (9) tidal breezes, (10) volcanic storms.

Chapter X., treating of cyclonic storms and winds, is one of the most interesting and valuable in the book. The tropical cyclones are first considered. The evidence of convectional action in these cyclones is considered, and it is shown that their distribution both in time and place points strongly to the theory that they originate through the overturning of great masses of air, due to unequal heating. But it is clearly pointed out to the pupil that it has not yet been directly shown that the temperature of the cyclonic mass is higher than that of the surrounding atmosphere at corresponding altitudes, a condition which, of course, must be satisfied before convection can take place. If this shall, hereafter, be shown not to be the case, the convectional theory will have to be abandoned.

In points like this, Prof. Davis' book is particularly good, for, all along, he has stated clearly not only what is certainly known, what is probable, and what is doubtful, but also what is not known. This prevents the student from forming misconceptions of the subject, or dropping into loose habits of thought.

The extra-tropical cyclones are closely compared with the tropical cyclones, and their points of likeness and difference shown. Two theories for their origin are discussed, and lines are indicated along which the rival theories may, some day, be tested, but here again, the fact is emphasized that much is not yet known, and that positive didactic statements are to be avoided.

Space will not permit even a brief mention of many other points to which we should like to call attention. The subjects of thunderstorms,