FOR GENERAL READERS. 



Vol. I. — No. 26. {New Series.) 



FRIDAY, JUNE 29th, if 



r Weekly, Price Sd. 

 L By Post. Sjd. 



CONTENTS. 



•PAGE 



Scientific Table Talk 601 



The New Rings of Saturn 602 



Jordan's Photographic Sunshine Re- 

 corder (?7A«.) 603 



Danger from Flies 604 



The Driftless Area of the Upper 



Mississippi ... ... ... ... 605 



The Homing Instinct 606 



General Notes 607 



The Polyparium Ambulans {ilhts.) ... 609 



Vegetative Modifications of Protoplasm 6 1 o 

 Natural History : 



The Sting of a Scorpion (illus.).,. 611 



Snakes in Burmah ... ... 612 



Dififerences in the Milks of Cows 612 



The Fossil Flora of Portugal . . . 



Miscellaneous Notes 

 The Intelligence of the Woodcock ... 

 Reviews : 



The Origin of Floral Structures... 



Proceedings of the Cleveland In- 

 stitution of Engineers 



Transactions of the Mining In- 

 stitute of Scotland 



Modern Science in Bible Lands... 



A Few Words on Portland Cement 

 Abstracts of Papers, Lectures, etc. : 



Royal Society 



Edinburgh Botanical Society 

 The Social Condition of the Babyloni: n 



PAGE 

 612 



613 

 613 



614 



614 



614 

 615 

 615 



61S 



616 



3 616 



The Effect of Oil on Waves 



Astronomical Ideas of the Negroes of 

 Central Africa ... 



-Mesmerism 



Correspondence : 



A Circle Problem. — Thunder- 

 storms and Lightning Accidents. 

 — A Plea for the Sparrows ... 



Recent Inventions 



Technical Education Notes 



Announcements 



Diary for Next Week ... 



Sales and Exchanges ... 



Selected Books 



Meteorological Returns 



PAGE 

 61S 



619 

 619 



621 

 622 



623 

 623 

 624 

 624 

 624 

 624 



SCIENTIFIC TABLE TALK. 



By W. Mattieu Williams, F.R.A.S., F.C.S. 

 The pictures of hailstones on pages 557 and 581 are very 

 interesting in connection witPi a theory put forward eight 

 or nine years ago by SchwedofF, a Russian philosopher. 

 He supposes that hailstones have an extra-terrestrial 

 origin, come to the earth from outside space, as meteorites 

 are known to come. 



This is a bold original theory, and has therefore been 

 flippantly pooh-poohed by scholastic scientists. Those, 

 however, who are addicted to thinking independently 

 will regard it very differently. I have carefully con- 

 sidered the subject, and without venturing to affirm that 

 all hailstones are of cosmical origin — that is, without 

 denying that some may be formed within our own atmo- 

 sphere, I have little or no doubt that some are picked up 

 from without by the earth in the course of its journey 

 in space. 



My chief reasons for believing this are the following. 

 It is a well-proved and established law that aqueous 

 vapour diffuses itself into a vacuum or a gaseous plenum 

 with a tension or elastic energy, proportionate to the 

 temperature to which it is raised. Also that the solar 

 rays are largely absorbed by aqueous vapour, and its 

 temperature is raised thereby. 



What, then, must happen when the sun shines on the 

 far-away extensions of our atmosphere, and on those of 

 the atmospheres of other planets, and on those of the sun 

 itself, all of which contain aqueous vapour ? 



Obviously such vapour must diffuse itself into space 

 farther and farther away so long as the solar rays main- 

 tain it in a gaseous condition. Therefore, if there were no 

 compensation, a continual evaporation of the surface 

 waters into the atmosphere, and a diffusion of this 

 vapour further and further into space must occur, until in 

 the course of a geologically short period our world would 

 be dry and arid as the moon. In like manner the 

 material of the polar snows and the seas of Mars would 

 speedily leave him ; so would the water of the vaporous 

 jacket of Venus, and of the deep envelope of Jupiter. 



But let us follow this outspreading vapour a little 

 further, limiting at first our attention to that which has 

 departed from the earth. What would happen to some 

 of it which, in the course of its outspreading, should 

 come within the night-shadow of the earth ? To answer 

 this, remember that radiation and absorption are correla- 

 tive ; good absorbers are correspondingly good radiators. 

 Such being the case, the vapour must rapidly 

 give out its heat when shaded from the sun and sur- 

 rounded by the temperature of space. The result of 

 this must be condensation, not merely to the liquid, but 

 to the solid state, into minute feathery crystals of hoar 

 frost. Inter-gravitation and other forces which I have 

 not space to describe in detail would operate to effect a 

 greater or less degree of aggregation of these solid 

 particles, and thus to form the snow-like material which 

 constitutes the inner portion of hailstones having any 

 considerable magnitude. 



The structure displayed in the engravings on pages 557 

 and 581 is easily explained by this hypothesis. The spheri- 

 cal nucleus is in complete harmony with the theoretical 

 structure of the original hailstone which, entering the 

 denser regions of our atmosphere, would at first be exter- 

 nally heated by friction, and thus an outer film would be 

 melted and volatilized. But this same friction would 

 speedily check its speed, far more speedily than the 

 outer heat could travel to aihy considerable depth through 

 the very bad-conducting ice. The velocity being thus 

 checked, another action would follow in the course of its 

 slower downward course through humid atmosphere. 

 The space-cooled mass would condense and crystallize 

 the atmospheric vapour around it, and this condensation 

 would become considerable in cases of violent tempest, 

 where the hailstones are whirled about by the wind, and 

 thus suspended for a considerable time before reaching 

 the earth. 



That hailstones may have an excessively low tem- 

 perature has been proved by actual experiment. As an 

 example, I refer to the Annales de Chimie ct Physique, 

 series 6, vol. 3, page 425 (1885), where Boussingault 

 records his observations on hailstones that fell in the 



