I might go on cataloguing in detail the many uses to which models may be put, but shall now mention only one more--perhaps the most important of all--their use in the education of the young. No method has yet been devised that is capable of giving so clear and accurate a conception of the principles of physical geography as a series of well selected models; models have, indeed, already been used for this purpose, but unfortunately their great cost has prevented their general use in schools. Since, however, the study of geography has been placed upon a new basis and a new life has been infused into it, many men have given their attention to the subject of models, and have experimented with a view to cheapen the cost of reproduction, which has hitherto prevented their wide distribution; and probably this objection will soon be remedied. The ability to read a map correctly,--to obtain from a study of the map a clear conception of the country represented,--is more uncommon than is usually supposed. Some of the recent methods of teaching geography are intended to cultivate this very faculty, but it is doubtful whether there is any better method than that which consists in the study of a series of good models in conjunction with a series of maps, all on the same scale and of the same areas. The value of a series of good models in teaching geology is so apparent that it need only be mentioned. It is often, for reasons stated above, far more valuable even, than field instruction. For the construction of a good relief map the first requisite is a good contoured map. To this should be added, when possible, a good hachured map, upon which the elevations of the principal points are stated,--if the interval in the contoured map is a large one,--and as much material in the way of photographs and sketches as it is possible to procure. The modeler should, moreover, have some personal acquaintance with the region to be represented, or, failing that, a general knowledge of topographic forms, and at least a clear conception of the general character of the country which he seeks to represent. This is very important, for it is here that many modelers fail: the mechanical portion of the work any ordinarily intelligent person can do. A model may be as accurate as the map from which it is made, every contour may be placed exactly where it belongs, and yet the resulting model may be,--indeed, often is--"flat," expressionless, and unsatisfactory. Every topographer in drawing his map is compelled to generalize more or less, and it is fortunate for the map if this be done in the field instead of in the draughtsman's office. But topographers differ among themselves: there may be, and often is, considerable difference in two maps of the same region made by different men; in other words, the "personal equation" is a larger element in a map than is usually supposed. This being the case, there is something more required in a