[18] L'Année Psychologique. Edited by Alfred Binet--with the Collaboration of H. Beaunis, Th. Ribot and Bourdon, Courtier, Farrand, Flournoy, Philippe, Vaschide, and Warren. Editorial secretary, Victor Henri. Fourth year. Paris: Librairie C. Reinwald. Schleicher Brothers, publishers. Pp 849. Price, 15 francs. [19] Introduction to the Study of North American Archæology. By Prof. Cyrus Thomas. Cincinnati: The Robert Clarke Company. Pp. 891. [20] Handbook of Nature Study for Teachers and Pupils in Elementary Schools. By D. Lange. New York: The Macmillan Company. Pp. 339. Price, $1. [21] The State: Elements of Historical and Practical Politics. By Woodrow Wilson. Revised edition. Boston: D. C. Heath & Co. Pp. 656. Price, $2. [22] How to Name the Birds. A Pocket Guide to the Land Birds and to the Principal Water Fowl normally found in the New England States, New York, Pennsylvania, and New Jersey, for the Use of Field Ornithologists. By H. E. Parkhurst. New York: Charles Scribner's Sons. Pp. 115. Price, $1. Fragments of Science. =Carbonic Acid and Glaciation.=--In a paper on Hypotheses bearing on Climatic Changes, Prof. T. C. Chamberlin takes up a suggestion of Tyndall's that the periods of terrestrial glaciation might be dependent upon the carbon dioxide of the atmosphere, the peculiar competence of which to retain solar heat he had demonstrated. Following out the doctrine of atmospheric loss on its own lines, although only in a tentative way as yet, he seems to find a rhythmical action that may in part explain the glacial oscillations. The idea, he says, hinges on the action of the ocean as a reservoir of carbon dioxide, and on the losses of the organic cycle under the influence of cold. Cold water absorbs more carbon dioxide than warm water. As the atmosphere becomes impoverished and the temperature declines, the capacity of the ocean to take up carbonic acid in solution increases. Instead, therefore, of resupplying the atmosphere in the stress of its impoverishment, the ocean withholds its carbon dioxide to a certain extent, and possibly even turns robber itself by greater absorption. So also, with increased cold the progress of organic decay becomes less active, a greater part of the vegetal and animal matter remains undecomposed, and its carbon is thereby locked up; and hence the loss of carbon dioxide through the organic cycle is increased. The impoverishment of the atmosphere is thus hastened and the epoch of cold is precipitated. With the spread of glaciation the main crystalline areas whose alteration is the chief source of depletion become covered and frozen, and the abstraction of carbon dioxide by rock alteration is checked. The supply continuing the same, by hypothesis, re-enrichment begins, and when it has sufficiently advanced warmth returns. With returning warmth the ocean gives up its carbon dioxide more freely, the accumulated organic products decay and add their contribution of carbonic acid, and the re-enrichment is