536 



SCIENCE 



[N. S. Vol. LIII. No. 1380 



the glacier at the cirque front, even dashing 

 a little upward on the opposite mountain side; 

 and then, rushing down the steep glacial cas- 

 cade where it cut off seracs and clogged cre- 

 vasses, it divided on the convex surface of the 

 lower glacier and overran both lateral mo- 

 raines but failed to reach the mid-extremity 

 of the tongue on the floor of the Allee blanche. 

 The total distance traversed by the slide was 

 about 8 kilometers according to the map, but 

 only 5 according to the text; the total descent 

 was from altitude 4,300 to 1,500 meters. The 

 time of descent of the first slide on Nov. 14, as 

 estimated by eye witnesses, was between 2 

 and 3 minutes; the velocity of movement was 

 the greater because winter snows had not yet 

 fallen on the ice in the great cirque. The 

 volume of the slide was roughly estimated at 

 between 4,000,000 and 5,000,000 cubic meters. 

 Dust of rock and ice was spread by the wind 

 blast of the slide, right and left of its course 

 on the glacier and the mountain flanks, for a 

 width of a kilometer or more ; trees were over- 

 turned by the blast outside of the lower lateral 

 moraines; a temporary lakelet was formed 

 where the right lower branch of the slide, 

 crossing the trough floor and ascending a little 

 on the farther side, obstructed the Dora Bal- 

 tea. The slide was evidently one of those 

 spasmodic efforts by which the Alpine moun- 

 tain faces, over-steepened by glacial sapping, 

 try from time to time to regain more moderate 

 slopes, such as they had in Preglacial time; 

 but the volume of the fallen rock was but a 

 trifling fraction of the spur from which it 

 was detached. 



W. M. D. 



EXTRA-MUNDANE LIFE: A COMMENT 



To THE Editor of Science: In discussing 

 the highly speculative subject of intelligent 

 life in other worlds it is well to keep in mind 

 two serviceable precepts of scientific reason- 

 ing : First, failure to prove that J. is -B is not 

 a proof that A is not B. Thus, failure to 

 furnish evidence that other worlds are inhab- 

 ited by intelligent creatures is not to be con- 

 strued as proof that such extramundane life 

 does not exist. Second, of two discordant 



propositions: A is B; A is C; one of which 

 must be true and for neither of which any evi- 

 dence is forthcoming, we are intellectually 

 bound to accord hospitality — not adoption but 

 hospitality — to the one which is marked by 

 the greater likelihood. Viewed without an- 

 thropometric bias this earth is, as we know, 

 one of the less important members of the sys- 

 tem to which it primarily belongs — a system 

 dominated by a single undersized yellow star. 

 If we had a time word corresponding to the 

 space word parsec, and also had more definite 

 geological knowledge of the past and future 

 duration of this planet, we might express 

 quantitatively the fact that the human race is 

 relatively a mere episode in the history of the 

 planet itself; while our increasing knowledge 

 of the Milky Way with its encircled disk of 

 stars must convince us that our solar system 

 is, in turn, only an incident in the history of 

 the stellar system to which it belongs. Which 

 is more probable, that this one insignificant 

 planet is the only world in which creatures ca- 

 pable of feeling and knowing have originated 

 and developed, or that multitudes of other 

 worlds have afforded both conditions and cause 

 for life, including intelligent life, and are the 

 homes of beings of both physical and mental 

 parts. The latter supposition seems to be in- 

 vested with incomparably greater likelihood. 

 Ellen Hayes 

 "Welleslet, Mass., 

 ■May 22 



SCIENTIFIC BOOKS 



The Health of the Industrial Worher. By 

 Edgar L. Collis and 'Major Greenwood, 

 containing a chapter on Reclamation of the 

 Disabled by Arthur J. Collis and an intro- 

 duction by Sm George Newman. London, 

 J. & A. Churchill, 1921. 

 The api)earance of the first English book on 

 industrial hygiene could not have been more 

 happily timed. With a combination of an in- 

 dustrial depression and a glutted labor market 

 there is a widespread tendency among Amer- 

 ican managers to scrap the elaborate person- 

 nel machinery established during the war — 

 " to safeguard the health and capacity of the 



