June 25, 1920] 



SCIENCE 



639 



appeared. It gives an interesting account of 

 the ethnology and culture of the peoples of 

 these islands. 



Henry Fairfield Osborn 



NOTES ON METEOROLOGY AND 

 CLIMATOLOGY 



THE EFFECT OF SNOW UPON THE GROWTH 

 OF WINTER WHEAT 



It has long been believed that a snow cover 

 is a beneficial factor in the growth of winter 

 wheat; but some doubt has recently been cast 

 upon this view, at least with respect to Ohio 

 and Illinois, for which the question has 

 been studied. Two short papers, one by Mr. 

 Clarence J. Eoot^ and the other by Professor 

 J. Warren Smith,^ have served as intro- 

 ductory to a longer discussion by Mr. T. A. 

 Blair.^ Professor Smith draws a clear dis- 

 tinction between the quantity of snowfall 

 with its subsequent effect and the effect of a 

 snow covering, for it may well be that a very 

 heavy snow will melt quickly and leave the 

 ground bare for a considerable time, or that 

 a very light snow will remain for a long time 

 unmelted on the ground. Thus, the question 

 of the relation of snow and winter wheat is 

 divided into two distinct aspects. 



The first aspect has been discussed by Mr. 

 Blair. His method of treating the problem is 

 two-fold: first, by the well-known method of 

 partial correlation, and second, by expressing 

 the yield in linear regression equations of the 

 form Y ^a -\- h^x^ -j- h^x^ -\- i^x^ ■-{-..., in 

 which T is the yield; x^, x^, x^, . . . are the 

 various weather elements, such as mean tem- 

 perature, total precipitation, sunshine, etc.; 

 and 6j, b,, h^, . . . are constants for a given 

 equation depending upon the data. In ex- 

 pressing such relationships, the author has 

 had to assume that there is a linear relation 



1 ' ' The Relation of Snowfall to the Yield of 

 Winter Wheat," Mo. Weather Bev., October, 1919, 

 Vol.47: 700, 4 figs. 



2 "The Effect of Snow on Winter Wheat in 

 Ohio," ibid., pp. 701-702, fig. 



3 "A Statistical Study of Weather Factors Af- 

 fecting the Yield of Winter Wheat in Ohio, ' ' Hid., 

 December, 1919, Vol. 47 : 841-847, 2 figs. 



between the weather and yield, which, as he 

 says, " is doubtful in cases of extreme weather 

 conditions," and also that the most important 

 weather influences have been included in his 

 equations. Of the latter, perhaps the most 

 important are temperature and precipitation, 

 although there are many other factors which 

 are not considered owing to lack of data, but 

 which are more or less directly related to the 

 weather, namely, hessian fly and other insects, 

 severe storms, hail, and loss of crop by storm 

 after it is cut. 



Taking the state of Ohio as a whole, Mr. 

 Blair finds that there is little evidence that 

 there are monthly values of weather elements 

 which exert a profound influence upon the 

 yield of wheat. After obtaining this negative 

 result, he proceeds to treat smaller areas of 

 the state and shorter periods than the month. 

 First, confining his area to Fulton coimty, 

 and his period to 10 days, he finds that there 

 are certain conditions of temperature and 

 precipitation — the former more than the latter 

 — operative over short periods, and these are 

 the dominant factors in determining the 

 final yield. 



His conclusions, which seem to cast doubt 

 upon the validity of the practise of the Bu- 

 reau of Crop Estimates in publishing crop 

 estimates as early as December 1, show that 

 for the state as a whole, a warm March and 

 June and a cool, dry May are favorable for 

 a high yield. There are certain critical stages 

 in the development of the plant, in which the 

 conditions during certain 10-day periods may 

 exert an important influence, especially in 

 northern Ohio. It is found that the weather 

 should be cool during the jointing stage, dry 

 during the development of the boot, warm 

 while the head is filling, and warm during the 

 last ten days of stooling. As to the quantity 

 of snowfall, it appears that a heavy fall of 

 snow in March is detrimental. Forecasts of 

 yield, earlier than May or June, believes Mr. 

 Blair, can be of little value, because of the 

 great influence of temperatui'e during those 

 months. 



The second aspect of the distinction drawn 

 by Professor Smith, was investigated by Mr. 



