910 



SCIENCE. 



[N. S. Vol. XVI. No. 414. 



7 :10 on the evening of July 12 and lasted 

 about twenty minutes. As the size of the 

 hailstones was very much larger than is usual 

 in this part of Canada, and as the storm was 

 accompanied by an unusual phenomen9n, 

 noted below, it seems worthy of record. 



The storm approached us from the south- 

 east, while we were near the divide between 

 streams flowing southwest to the English 

 River and Lake Winnipeg, and those flowing 

 easterly towards the Cat River, a large stream, 

 or rather a chain of lakes tributary to the 

 Albany River. The hailstones varied from 

 about the size of buckshot or small marbles 

 to spheres and other forms over one inch in 

 diameter. One large stone, in shape a com- 

 pressed ovoid, measured 1.25 X l-'i'S X 2.25 

 inches. Others over 1.50 inches in diameter 

 were plentiful. The smaller hailstones were 

 almost invariably of clear ice with a small 

 white nucleus of snow. The larger ones 

 were usually white with a transparent nu- 

 cleus. Many of the pellets, both small and 

 large, were almost perfect spheres, but not 

 infrequently the large ones took the form of 

 disks, thin and transparent in the middle, 

 with thicker edges of snow, reminding one 

 of the shape of the red blood corpuscles or the 

 fly-wheel of a sewing machine. One large 

 pellet of tWs kind measured 1.75 inches in 

 diameter and. the circular rim was one inch 

 thick, the middle portion of the disk being 

 transparent. The disks were more often ellip- 

 soidal than circular. The surface was gen- 

 erally warty or mammillated, as if produced 

 by the coalescence of a. number of independent 

 hailstones, whereas that of the spheres and 

 ovoids was usually smooth. 



The most interesting feature accompanying 

 the storm was the behavior of the moss carpet 

 flooring the spruce forest everywhere. In this 

 portion of the district this surface cover con- 

 sists almost wholly of a dense mat of the moss 

 Hypnum triquetrum, through which are woven 

 a tangled mass of roots, living and dead. The 

 thickness of the cover varies from a few 

 inches to over a foot. During the storm there 

 was no wind noticeable in or near the camp. 

 The moss carpet in front of and underneath 

 our tent was seen and felt to be heaved in 



waves, the crest lines, just in front of the teut 

 door, sometimes raising the moss as much as 

 a foot above the normal position. These un- 

 dulations traveled in the same direction as 

 the storm was moving, i. e., towards the north- 

 west. No two crests were seen to be in exist- 

 ence at the same time, but the field of view 

 was limited to an area of about thirty feet 

 across in the direction the waves were mov- 

 ing. The movement began, or at least was 

 first noticed, near the end of the hailstorm, 

 and continued for some time after the rain 

 and hail had ceased to fall, lasting for a 

 period between five and ten minutes. The 

 writer has frequently been in the moss-car- 

 peted spruce forests of central Canada during 

 thunder storms, but has not happened hereto- 

 fore to have met a similar phenomenon. The 

 cause of the movement seems to lie in the 

 fact that the moss cover retained the water 

 which first fell upon it, soaking it up like a 

 sponge and hence became nearl,y air-proof. 

 The air underneath, in the interspaces be- 

 tween the boulders and fallen timber upon 

 which the moss lies, would sympatheticall.y 

 respond to slight variations in the barometric 

 pressure and cause the moss to rise and fall 

 as the pressure decreased or increased. Sooq 

 after the movement ceased many of the spaces 

 that before contained only air were filled with 

 water, and walking on the moss was not un- 

 like walking on a wet sponge. 



Alfred W. G. Wilson. 

 JfcGii.1, University, Montkeal. 



WHAT IS NATURE STUDY? 



As was stated in Science for June 20, of 

 this year, there seem to be, among educators, 

 many confiicting definitions in the attempt to 

 answer the above question. Bearing on this 

 subject the following letters have been re- 

 ceived from eminent scientific men of this 

 country. They appear in the order in which 

 they were received. W. J. Bead. 



AGRICUI.TURAL COLLEGE, MiCH. 



The present movement toward developing 

 and spreading an interest in nature studies 

 is one of prime importance. Our Americau 

 children are, after all the efforts thus far 

 made, woefully lacking in interest in natural 



