414 



NATURE 



[January 25, 191 2 



already a fair knowledge of magnetism, of heat, and of 

 chemistry, he can very profitably begin the study of statical 

 electricity, which can be made quickly to lead on by well- 

 understood steps to 111' ^iiidv of electric currents. 

 Clifton, January 2. A, M. Worthington. 



Olazed ProBt. 



A REMARKABLY good instance of glazed frost occurred 

 in the London suburbs on Thursday morning, January 18, 

 nnd evidently the same phenomenon was observed over a 

 wide area in the south of England. A touch of real 

 winter had spread rapidly over the country, and a strong 

 and cold easterly wind was blowing, associated with the 

 European anticyclone where the barometer was 31 inches, 

 and with an area of low barometer readings over the 

 Atlantic in fair proximity to our coasts. These conditions 

 occasioned a heavy fall of snow over the northern and 

 .Midland portions of England, but there was copious rain 

 in the south of England, with the air temperature at or 

 slightly below the freezing point. 



The trees and shrubs, as well as all ornamental work, 

 in the garden were coated with clear ice varying in 

 thickness from a tenth to two-tenths of an inch. 



I plucked a twig with its ice coating on Streatham 

 Hill and carried it with me to Fleet Street, where on 

 arrival an hour later the twig remained encrusted with 

 ice. 



The shrubs and wire arches, &c., were exceedingly 

 beautiful, but there was no ice coating within 2 feet of the 

 ground — my lowest screen temperature was 31°. 



The following description of the phenomenon is taken 

 from "The Observer's Handbook," published by the 

 Meteornldt^ir.'il Office, London, 1910 : — 

 " Gi.A/i n I KosT. (German Glatteis, French 1 



''A iiaiisiiaicnt smooth coating of ice covering 

 buildings, &c. The phenomenon is usually caused by rain 

 which freezes as it reaches the ground, and thus covers 

 all objects with a coating of smooth transparent ice. It 

 is very rare in our climate, but on the Continent or in 

 America it is more common. The weight of the ice which 

 collects is frequently sufficient to cause damage to tele- 

 graph wires, trees, &c. It is probable that the rain in 

 these cases consists of supercooled drops of water." 



Scott's " Elementary Meteorology," p. 116, has an 

 excellent reference to a remarkable instance of glazed frost 

 which occurred in France on January 22-24, '870, taken 

 from the Comptcs rcndtis of the Paris .Academv of 

 Sciences. Chas. Harding. 



The Isothermal Layer of the Atmosphere. 



May I be permitted through the medium of your columns 

 to suggest briefly what appears to me a possible explana- 

 tion of the isothermal layer of the atmosphere, or strato- 

 s})here ? 



It is, I believe, generally admitted by astronomers that 

 the swarm of small cosmical bodies reflecting light from 

 the sun, known as the Zodiacal Light, extends bevond the 

 earth's orbit, but lies outside the earth's atmosphere. My 

 proposition is that heat received by these bodies from the 

 sun is reflected, some of the heat reaching our atmosphere 

 and penetrating its layers as far as the outer limits of the 

 cloud layer. The heat thus supplied from above would 

 be supplemented by heat received through the agency of 

 terrestrial radiation, a larger supply being accumulated 

 above the land than above the ocean. The greater height 

 of the isothermal above the latter might be accounted for 

 in this manner. 



This suggestion is thrown out for the purpose of elicit- 

 ing criticism, and in the hope of gaining information. 



Campbell Hepworth. 



2 .\mherst Road, Ealing, W., January 15. 



Concentric Joints in Ice. 



In walking over a piece of water-logged ground, I noticed 

 several small shallow pools which had frozen over. .A 

 number of rings, more or less parallel to the edges, were 

 visible as in the plan. The water was found to be a 



NO. 2204, VOL. 88] 



couple of inches below the top of the ice, and the 

 were vert' ' ' s, along which the ice could be r 

 broken, i ich of these concentric *' joints 



bulb form heated in the section (roughly to 



was found in various stages of development, the bill 

 nearest the centre being, as a rule, the most perfe 

 developed. The full bulb projected about three-quarters 



SccTiora 



Platte 0/ wtakrteai 



Surface of Y^ a Ctr , 



an inch below the ice-sheet, which did not vary much froa 

 five-eighths of an inch or so in thickness. 



I should be interested to hear if any of your reader= -- 

 explain the somewhat peculiar formation described ab 



Harold J. F. Golri 

 St. Stephen's House, Victoria Embankment, 

 Westminster, S.W., January 15. 



The Late M. Radau. 



In the obituary notice of M. Radau printed in 

 " Notes " columns of N.\tlre (Januar>- 11, p. 3* 

 notice the statement : " .•Vt no time does he seem to 

 held an official post as a practical astronomer." 

 words fail to do complete justice to this distinguished 

 of science. On M. Loewy's death M. Radau was appointei 

 to succeed him as " le Membre du Bureau des Longitude 

 charge de la redaction de la Connaissance des Temps, 

 in this capacity he signed the " avertissements " t. 

 volumes of the Connaissance des Temps for the years ^^H 

 1912, and 1913 as the official responsible for their con^^H 



January 20. 



A. M. \\'. IV 



The Luminosity of Cats* Eyes. 



I have repeatedly observed the brilliancy of cats' eye 

 in the dark in particularly favourable circumstances, 

 have a brilliant incandescent light in my hall, and severa 

 cats on the premises. The entrance drive is in a line witl 

 the door and the hall lamp. When I call a cat in th 

 chances are that if there she simply sits and looks at me 

 presenting the spectacle of two small incandescent light 

 glowing out of the darkness. I 'c!'^' -i^- --ver, and cat ar 

 all three in line, as observed rschel. 



.\. R. Hunt. 



Southwood, Torquay, January 23 



