The North West Passage 1534-1859, compiled by Edith G. Firth, with an introduction by H.C. Campbell

an ice crystal and the thickness of the ice sheet, h, is usually 3: 70 in natural freshwater bodies, whereas in the laboratory tank ice crystals may grow to 10 to 12 cm. in cross-section, though the thickness of the experimental ice sheet in the tank is only 7 mm. thus giving a ratio of 10: 0.7 or 12: 0.7. Consequently, the mechanical properties of the natural ice sheet may be quite different from those of the ice sheet grown in the laboratory, since it is lacking the similitude ratio 3: 70. To make the model similar to the natural ice sheet, the model ice sheet would have to be grown by a method that would result in the model sheet consisting of ice crystals 0.5 to 0.6 mm. in cross-section. This illustrates the problem of similitude as treated by Lavrov. Conditions for the similitude of the ice of models and methods for achieving it in laboratory-grown ice sheets are discussed in detail. A few minor Aaws appear in this masterly monograph. As the making of laboratory models of ice, so the reinforcement of ice in situ is a quite important physical-glaciological problem that might well have been dealt with in a fifth chapter (see Ref. 3). One misses in the generous list of references (152 titles) the work of K. F. Voytkovskiy4 on the mechanical properties of ice. Another, and more important flaw is the quality of the paper. This reviewer feels that Lavrov’s work deserved to have been printed on better paper. ANATOL J. SHNEIDEROV”