412 



NATURE 



[March i, 1894 



In connection with Coulomb's law, the statement that 

 F = Q/r- (Art. 581) is "strictly true only when the two 

 bodies are in a vacuum," requires a little more elucidation 

 than the author gives. Similarly the explanation of 

 polarisation, the definition of specific resistance (in terms 

 of the metre and square millimetre), the statement of 

 Ohm's law, and the laws of thermo-electric phenomena 

 require more detailed and accurate treatment. 



The paragraphs on recent work, such as Hertz's ex- 

 periments, theories of magnetism and electrolysis, and 

 modern theories of the ether, are far too meagre to be 

 of any service ; they give no information even to the 

 student who is able to read between the lines. 



Apart from thesa points, the book appears to present a 

 fairly reliable exposition of the elements of the subject, 

 which may justify its issue as a separate volume. 



Meteo-Tdogy. By H. N. Dickson, F.R.S.E. (London: 



Methuen and Co., 1893.) 

 In this little book the author has attempted to lay down 

 "a certain amount of 'permanent way' specially adapted 

 to practical purposes, but at the same time leading to- 

 wards the more theoretical grounds of modern research." 

 The fundamental facts and principles stated in the 

 earlier chapters furnish the inquirer with much of 

 the necessary stock-in-trade of information culled from 

 other branches of science; as, for example, the behaviour 

 of gases under varying conditions of temperature and 

 pressure. Cyclones and anticyclones receive some- 

 what detailed consideration, but the account is very 

 intelligible, and the mathematical expressions are of the 

 simplest character. The present position of meteorology 

 in regard to weather-forecasting is very clearly and im- 

 partially stated. In the chapter on mstruments the 

 author leaves a little to be desired in the shape of illus- 

 trations and descriptions, especially as he aims at pro- 

 ducing a practical treatise. An excellent account of 

 cloud classification is given. The relation of meteorology 

 to agriculture is a subject of great practical importance, 

 and this is carefully discussed in the final chapter. 



The author has availed himself of all the most recent 

 sources of information, both British and foreign, and the 

 references to original papers form a valuable feature of 

 the book. To all who desire to carry theirmeteorological 

 observations beyond the mere hobby stage, we heartily 

 commend this little book. 



posing an edifice has been built, and the only "variant " of it 

 deserving of consideration is to the effect that the price of the 

 big egg was five instead of two francs. I may add that this- 

 simple story was published by the late owner of the egg, the 

 Baron Louis d'Hamonville, in the Bulletin of the French Zoo- 

 logical Society for 1891 (tome xvi. p. 34), 



Alfred Newton. 

 Magdalene College, Cambridge, February 24. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 7nanuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. \ 



Great Auk's Egg. 



Imagination has long had a large share in the accounts 

 given of the Gare-fovvl or Great Auk, notwithstanding the efforts 

 of those who have tried to set forth nothing but the truth on 

 the subject, yet I do not call to mind meetmg with so " many 

 inventions " regarding it as have appeared in the newspapers 

 within the last week, on the occasion of the recent sale of a 

 specimen of the egg of that bird. I should occupy too much 

 space were I to dwell upon them ; but 1 would ask for the 

 admission of a few lines in which to state what is known exactly 

 of the origin of that specimen, which I well remember in the 

 collection of the late Mr. Yarrell. He told me, as he told 

 others of his friends, that he bought it in Paris ; and, to the best 

 of my belief, not many years after the peace of 1815. In a little 

 curiosity-shop of mean appearance, he saw a number of eggs 

 hanging on a string ; he recognised one of them as an egg of 

 Alca impeiinis, and asking their price was told that they were 

 one franc apiece, except the large one, which from its size was 

 worth two francs. He paid the money and walked away with 

 the egg in his hat. That is the whole story on which so im- 



Frost-Cracks and " Fossils." 



Several letters appeared in Nature last winter describing 

 some of the more interesting plant-like forms due to frost acting 

 on various surfaces, and both Prof. Meldola and myself drew 

 attention to the possible deceptions which might arise from a 

 preservation of such patterns as fossils. I yesterday met with 

 a striking case illustrating this. It was at Cullercoats, on the 

 Northumberland coast. There had been a slight frost the night 

 before, and the surface of a talus of semi-liquid mud at the foot 

 of a low cliff of boulder clay (actually on the line of the great 

 Fault known as the "Ninety-Fathom Dyke ") was found 10 be 

 indented with cracks about \ to i an inch deep and \ of an 

 inch in breadth. These cracks were disposed in beautifully 

 branched patterns bearing a surprising resemblance, in out- 

 line, to some of the more subdivided sea-weed fronds. A sandy 

 beach lay close by, and a high wind was blowing the sand on to 

 the mud. It was obvious that the sand would soon fill in the 

 frost-cracks under these conditions. The cracks would thus be 

 preserved, and if at any future time the mud surface be again ex- 

 posed it will be found covered with sand (or, after induration of 

 the mud and pressure of overlying material, sandstone) casts of 

 what it would be very difficult to believe were not vegetable 

 organisms in an unusually perfect state of preservation. 



Newcastle-on-Tyne, February 25. G. A. Lebour. 



The Origin of Lake Basins. 



I WISH to draw the attention of your correspondents, Messrs. 

 Aitken and Tarr, to p. 94 of the Geological Magazitte, vol. iv. 

 1876, in regard to the manner in which, in all probability, the 

 greater number of the lakes in British North America were 

 formed. There are, however, doubtless many other causes by 

 which lake basins have been formed. The object of my notice, 

 was simply to point out that the ice need not be supposed to have 

 exerted any extraordinary or abnormal influence in scooping out 

 rock basins which have subsequently become lakes. 



Ottawa, February 16. Alfred R. C. Selwyn. 



Note on the Habits of a Jamaican Spider. 

 Observing in your issue of January 11, p. 253, an interesting: 

 note on the Nephila madagascarieiisis, I am prompted to send 

 you some unpublished observations on the Jamaican species,. 

 N. clavipes. They are from the MSB. of the late Mr. William 

 Jones (concerning whom s^cjourn. Inst, /atnaica, 1893, p. 301), 

 and date from over fifty years ago. The record begins : "Aranea 

 clavipes, or the great yellowish wood-spider. I fancy Sir Hans 

 Sloane must have been misinformed when he states that this 

 spider's web will not only stop small birds but even pigeons. I 

 will venture to assert that its strength would not even endure the 

 struggling of the smallest humming-bird." But below is an- 

 other entry : " Dec. 25, 1839. I wronged the accuracy of Sir 

 H. Sloane's statement ; a little boy returning from an errand 

 brought me a little black and yellow bird that he found entangled 

 in a web of ^. clavipes." After this he adds a more general 

 statement concerning the spider : "St. Thos. ye East, on bushes 

 and outhouses, — I found in the old cooper's shop at Slamans 

 Valley Est. in Portland, many hundreds of these, some of a 

 monstrous size. These spiders weave an almost large [sic) 

 spiral web, yellow and strong, Hke silk, glutinous or viscid, 

 and well adapted for arresting the flight of large insects. I 

 have frequently seen some of their lines two or three yards long. 

 Butterflies appear their favourite food. They form an oblong 

 oval cocoon of a white substance like soft chamois leather, out- 

 side composed of little round-shaped compartments ; the cocoon 

 is covered over with a mesh of strong yellow thread or silk. 

 Finally he gives a technical description of the spider, which need 

 not be quoted. The spider's size is said to be I to i^ inches la 

 length, with the fore-legs 2A inches long, the second pan- 2 inches,, 

 the third pair i inch, and the fourth pair 2 inches. 



NO. 1270, VOL. 49] 



