Throughout the world climate is one of the determinants of building practice; nowhere is this more evident than in the great northern continental interiors of which Canada claims so large a share. This publication is indeed apposite, for in recent years the development of large-scale construction by numerous public authorities has been marked, especially in connexion with defence programmes and the exploitation of natural resources. Eighty-four climatic maps covering all the normal requirements are here presented; for example, we find winter and summer design temperatures on a percentage basis, and mean annual totals of degree days below 65° F. as a basis for design of heating systems. To the glaciologist, the maps referring to snowfall and to the limits of permanently frozen ground will have decided interest. The relationship of the latter to other climatic elements is by no means simple. Among the snowfall maps, that showing the computed maximum snow load likely to occur is noteworthy; in parts of Quebec it may exceed 90 lb./sq. ft. (10.12 kg./cm.²). The greatest recorded depths of snow on the ground lie through south-east Labrador, apart from small areas in British Columbia at high altitudes. The mean annual snowfall is also greater in south-east Labrador than anywhere else in Canada; so far as observations go, some places average over 200 in. (5 m.). The maps are clear and well printed; a large amount of information is efficiently displayed, in this compact, unpretentious and very soundly conceived atlas.