Comparing Wangen with Florissant, it appears that the Colorado locality is more extensive, more easily worked, and provides many more well-preserved fossils. On the other hand, Wangen has proved far richer in vertebrates and crustacea, and on the whole gives us a better idea of the fauna as it must have existed. Florissant far exceeds Wangen in the number of described species, but this is only because it has so many more insects. Each locality furnishes us with extraordinarily rich materials, enabling us to picture the life of Miocene times. Each, by comparison, throws light on the other, and while the period represented is not sufficiently remote to show much evidence of progressive evolution, it is hard to exaggerate the value of the facts for students of geographical distribution. Much light may also be thrown on the relative stability of specific characters. Work on the Florissant fauna is going forward, though not so fast as one could wish. It is very much to be hoped that the Wangen quarries will receive attention before many years have passed. Labor is comparatively cheap in Germany, and with a force of a dozen men it would not take long to open up the quarries and get at the best beds. It is really extraordinary that no one has seen and taken advantage of the opportunities presented. Probably no obstacles of any consequence would be put in the way; at least the owner of the quarries came by when we were digging, and expressed only his good will. With new researches in the field, combined with studies of the rich materials awaiting examination at Zurich and elsewhere, no doubt the knowledge we possess of the European Miocene fauna could be very greatly increased, to the advantage of all students of Tertiary life. THE THEORY AND PRACTISE OF FROST FIGHTING[1] [1] Some of the instruments used were obtained through a grant from the Elizabeth Thompson Science Fund. BY ALEXANDER McADIE BOTCH PROFESSOR OF METEOROLOGY, HARVARD UNIVERSITY ONLY in recent years have aerologists given much attention to the slow-moving currents of the lower strata of the atmosphere. These differ greatly from the whirls and cataracts of both low and high levels which we familiarly know as the winds. The upper and larger air streams play a part in the formation of frost, and we do not underestimate their function; but primarily it is a slow surface flow, almost a creeping of the air near the ground, which controls the temperature and is all-important in frost formation. So important is it that the first law of frost fighting may be expressed as follows: Where air is in motion and where there is good circulation, frost is not so likely to occur as where the air is stagnant.