314 



NATURE 



Feb. 3, 1 88 1 



ends — and when they touch, weld together, and]their surfaces 

 become metallic, like graphite. 



Diamonds heated in charcoal tubes were suddenly changed 

 aid became c:inductors. Still more remarkable effects were 

 produced when he used collaterally with the 6oo Bunsens 135 

 Muncke with zincs it,\ in. high and 195 in. wide. With these 

 sugar-charcoal was volatilised immediately. 



I think it may be inferred frim these facts that even at the 

 temperature of a po-.verful electric arc eniugh charcoal vapour 

 may be present to for,n its spectrum, and there i, little doubt 

 that the temperature of discharge of a good inductorium com- 

 bined with a sufficient condenser is still hotter than the arc. 



It is to be noticed that Despretz in these experiments antici- 

 pated Dr. .Siemens's electric farnace. He mentions that he fused 

 375° grains of platinum in a few minutes, and could have done 

 more had he had a larger crucible. R. 



A Case of Fascination 



Some years ago it was my fortune to witness a case of " fasci- 

 nation" b3tvveen a large striped snake and a medium-sized toad. 

 When first seen they were about fifteen inches apart. The snake 

 lay in a coil with its head thrust out towards its victim, and 

 moving slowly, its eyes glittering and its tongue darting 

 incessantly. 



The toad was standing on the very tips of its claws, with its 

 limbs rigidly drawn up to their full length, its eyes fixed upon its 

 captor and fairly bursting from their sockets, its mouth covered 

 with foam, and its wliole body swaying to and fro, and seeming 

 just ready to pitch forward upon its face. 



The movement of the snake became more and more rapid, and 

 the agitation of the toad more intense, until the space betueen 

 them was reduced to so ne three or four inches, when the snake 

 opened wide its mouth, and the laboured breathing of its victim 

 stopped short in a low guttural m 5an. 



At this point my own agitation became so great that, seizing a 

 heavy stone, I finished the snake at one blow. The instant the 

 snake was struck the toad fell backward as suddenly as though 

 itself had been hit, and lay upon its back for some minutes 

 with no signs of life. • At length it gained its feet and b.'gm to 

 creep languidly away. J. T. Brow x ell 



Lyons, N.Y., January 18 



Birds Laying in January 



As a proof of the unusual mildness of the weather just previous 

 to the intense frost and severe snowstorms most parts of the 

 country have lately been suffering from, it may interest some of 

 your readers to learn that njt far from this place, on the 13th 

 Jan., a wren's nest with seven eggs in it, quite fresh, was taken. 

 The nest I have in my pjssession, and it bears every evidence of 

 having been lately tenanted. The eggs, I am sorry to say, are 

 broken; they were placed in a cup for .safety, and were most 

 unfortunately knocked down when the room was dusted, giving 

 however unmistakable pro ^f of their having been but lately laid. 



I do not know whether there is any instance on record of a 

 wren's nest having been found in January before. 



John H. Willmore 



Queenwood College, near Stockbridge, Hants, January 28 



Vibration of Telegraph Wires during Frost 

 While walking with my son by the Liverpool, Crosby, and 

 Southport Railway between Crosby and Hall Road stations he 

 called my attention to the telegrai)h wires, which were in a state 

 of rapid vibration. The day was frosty, the time u. 30 a.m., 

 and the sun, which had been showing us a bright di-k through 

 the haze, was beginning to throw out rays and shine a little 

 strongly. At first I thought the movement must be only apparent 

 — a mere optical delu-ion— astheair was perfectly calm. A closer 

 examination convince J me to tlie contrary, as the under part of 

 the wires were covered with pendant ice needles, a sort of rime, 

 w hich moved to and fro indicating a torsional or twisting vibration 

 of the wires, and as the rapidity of the vibrations decreased this 

 was more clearly .seen. In about five minutes the movement cea,ed, 

 and I have not noticed it since, though I have frequently passed 

 under the wires on my way to skate. Can any of your corre- 

 spondents account for the phenomenon? It appeared as if in 

 some way connected with previous contract'on by the frost and 

 .sudden expansion in jerks by the sun'.s rays. My son informs 



me that two years ago, during a frost, he no'iced the strained 

 wires of a garden-fence behaving in the same curious way. 

 Park Corner, Blundell sands T. Mellard Reade 



"Mock Sun" 



I SEND a sketch of a parhelion which I saw from the East 

 Cliff, Hastings, on Thursday, January 20, at 3 p.m. The 

 crescents above the sun were fairly bright and well developed, 

 and there were faint traces of a second ring outside, and some 

 distance from, the first. 



^ 



\ 



There was a slight fog at the time, with a north-east wind and 

 Jiard frost, which has continued up to this time. We have had 

 no snow here since that "terrible Tuesday," the l8th. 



I do not remember ever having seen this phenomenon before, 

 except in pictures of the Arctic Regions. 



St. Leonards, January 24 J. E. H. Peyton 



ON SOME RECENT CHARTS AND MAPS OF 



CURVES OF EQUAL MAGNETIC VARIATION 



OR DECLINATION 

 CINCE the year lyor, when Halley published his 

 *--' fatnous chart showing curves ';of equal magnetic 

 variation for the Atlantic and Indian C)ceans, the con- 

 struction of similar charts, amended and enlarged as data 

 increased, has been of great interest to magnetic science 

 and of practical value to the navigator. 



Halley's chart of 1701 was expanded to embrace the 

 navigable parts of the whole world, and brought up to 

 the epoch 1756 by Mountaineand Dodson, whose labours 

 were followed by those of Churchman in 1794, Yeates in 

 1817, and Hansteen (for several distinct epochs between 

 1600 and 1787) in 1819. In 1833 Barlow's chart, together 

 with curves for the North Polar regions, accoinpanied a 

 descriptive paper in the Phi/. Trans, for that year. 



In 1840 Gauss and Weber's charts of theoretical curves 

 of the three magnetic elements for the whole world, 

 including special Polar charts, were published. These 

 curves were culculated on the basis of a mathematical 

 theory founded upon a large number of observations 

 fairly distributed over the surface of the globe. 



About this latter period the practice of ascertaining 

 the errors of the compass on shipboard (as due to the 

 effects of iron) for every ship in the Royal Navy, at 

 certain periods and on change of magnetic latitude, was 

 established by the Admiralty on the recommendation of a 

 compass committee specially appointed to consider the 

 question of compass efficiency and management. This, 

 as bearing on the subject under review, was an important 

 step towards obtaining reliable data for the construction 

 of Variation charts now becoming so essential an element 

 in navigation. 



Following on this, Archibald Smith's mathematical 

 investigations of the theory of the deviations of the 

 compass on board ship enabled Sabine to correct ob- 

 servations made in the Atlantic and the Antarctic Oceans 



