HARD WICKE'S SCIENCE- G OS SIP. 



167 



The conversazione of the Royal Society took 

 place on the 17th ult. Astronomy presented its 

 usual fascinating aspect. Professor Norman Lockyer 

 exhibited first a group of sun-spots, photographed in 

 India as they were passing over the solar surface, 

 and showing a succession of remarkable changes, 

 suggestive of terrestrial cyclones, as they traversed 

 the visible face of the sun. The greatest curiosity was 

 awakened by the professor's photographs of the 

 temples at Karnak and Edfou, in Upper Egypt. 

 There is now a theory that these famous structures 

 were oriented in such fashion that the rays of the sun 

 at 6 A.M. and p.m. on June 21 traversed the whole 

 central aisle of these edifices — in other words, that at 

 least six thousand years ago there was in Egypt a 

 people sufticiently advanced to know astronomically 

 the true length of the year and to determine with 

 precision such data as they needed for their daily 

 sacrifices. The same kind of astronomical motive is 

 supposed to have prevailed with the builders of the 

 huge monoliths of Stonehenge. At the instance of 

 Mr. Norman Lockyer, the Egyptian Government 

 sent out on June 21 observers to Karnak and Edfou 

 to make observations of the shadows which the lines 

 of the temple will make with its principal axis, and 

 as the motion of the sun in the heavens is known, it 

 may be possible to argue backwards from these data 

 to the probable age of the temples. Similar obser- 

 vations were made on Salisbury Plain, with the 

 • curious result, perhaps, of learning from the sun's 

 motion in the ecliptic how long ago it is since the 

 stones of that huge place of sacrifice were placed in 

 position by a relatively advanced race of people 

 inhabiting these islands thousands of years ago. 

 Mr. Francis Galton explained in the Council Room 

 his method of personal identification by means of 

 finger prints. It is a curious fact that the small 

 papillary ridges on the bulbs of the fingers, and on 

 the inner surfaces of the hands and feet, persist from 

 youth to age, and are the most unchanging, and 

 apparently the surest means of pronouncing on any 

 human being's identity. With exact anthropometric 

 measurements and descriptions, science is circum- 

 venting the criminal classes, and the time will 

 probably come when to the evil-doer Mr. Galton's 

 pictures of the finger tips will be a means of deciding 

 who's who that law-breakers will positively detest 

 and dread. Among the instruments Mr. Wimshurst's 

 improved influence machines deservedly attracted a 

 large amount of attention ; but, perhaps, the most 

 interesting of recent electrical achievements is Mr. 

 Crookes's volatilisation of metals. The distinguished 

 chemist and physicist has discovered that he can 

 evaporate gold, silver, and other metals by the 

 electric current. This is accomplished without accu- 

 mulation of heat, and what looks like the vapour of 

 gold settles as a thin transparent film on a surface of 

 glass. In transmitted light the hue is first ruddy, 

 then, as it becomes denser, greenish and faint yellow, 

 and only finally golden when the film is thick enough 

 to prevent light passing through. A curious and 

 instructive magnetic phenomenon was exhibited by 

 Mr. Shelford Bidwell, in a nickel pendulum which 

 was shown to be magnetic when cold and non-magnetic 

 when heated to about 300° C. Mr. Francis Darwin 

 displayed an instrument called a cup-micrometer for 

 measuring the rate of growth of a plant, while 

 Mr. Walter Gardiner has devised instrumental means 

 to determine the forces concerned in the absorption 

 and flow of water in plants. Mr. Arthur Clay- 

 den, M.A., showed by means of the electric lantern 

 some fine meteorological pictures of clouds, taken by 

 the camera in such style as enormously to simplify 

 the study of cloud formation, a department in which 



a good deal remains to be done. Some fine negatives 

 of hoar-frost were thrown on the screen, the pictures 

 bringing into strong relief the manner in which the 

 ice crystals form on the margins of leaves, the loose 

 fibres of a string, and the thorns of a briar, and the 

 tendency of these crystals to arrange themselves in 

 line with the direction in which the wind is blowing. 



Atmospheric Nitrogen and Root-Tubercles. 

 — Two American chemists, Messrs. W. O. Atwater 

 and C. D. W^oods, have published in the American 

 Chemical Jotirnal the results of a large number of 

 experiments they have been making on the important 

 subject of the acquisition of atmospheric nitrogen by 

 plants. They experimented with peas, oats, and 

 corn, and they conclude that nitrogen is readily 

 absorbed from the atmosphere by these plants, where 

 treated with "soil-infusion," and that the gain of 

 nitrogen is dependent on the number of root-tubercles 

 which the application of " soil-infusion " induces. It 

 should be remembered, however, that these root- 

 tubercles have been found to be literally nests of 

 bacteria, so that the latter may probably produce the 

 nitrogen by assisting in the nitrification of the soil. 



Atmospheric Nitrogen and Leguminos/e. — 

 Experiments have been conducted by two French 

 chemists, Messrs. Schloesling and Laurent. It has 

 long been suspected that the natural order of plants 

 Leguminosse had the power somehow of absorbing 

 atmospheric nitrogen. The leguminose plants ex- 

 perimented upon were grown in closed vessels, which 

 were so arranged that the gases introduced and with- 

 drawn could be accurately measured and analysed. 

 They found that when the leguminose plants were 

 watered with an infusion of nodosities from other 

 plants of the same order, there was an absorption of 

 nitrogen much greater than could be put down to 

 errors of experiment. On the other hand, when the 

 leguminose plants had not been inoculated in this 

 way, and were therefore free from nodosities, no such 

 absorption of nitrogen was observable. It is believed, 

 therefore, these experiments demonstrate that under 

 the influence of microbes leguminose plants can fix 

 and utilise the gaseous nitrogen of the atmosphere. 



Eriophorum latifolium. — It is stated in 

 Syme's " English Botany " (vol. x., p. 76), that the 

 downy-stalked cotton-grass {Eriophorum latifolium) 

 is "rare in the south of England." Being in the 

 neighbourhood of Fair Mile, near Esher, Surrey, on 

 the iSth inst., I noticed what I believe to be a very 

 large bed of it, the mass of cotton-like heads at- 

 tracting attention and admiration even at a distance. 

 The plants were growing in a morass surrounding a 

 pond, locally called Black Pond. Though familiar 

 with the locality many years ago, I had not visited it 

 for some years and was struck with the appearance. 

 It may be mentioned that the nearest railway station 

 is Oxshott (the name really means Oakwood, but the 

 L. & S. W. R. has now fixed upon it one of the 

 local spellings, suggesting the idea of bovine slaughter 

 at the place), on the new line from Surbiton to 

 Guildford. Although the spot gives the idea of 

 complete sequestration, it is in fact only a few 

 minutes' walk from the high road between Esher and 

 Cobham, near what is called Fair Mile. If I am 

 wrong with regard to the species, I should be glad 

 to be corrected. — W. T. Lynn. 



Coccus cataphractus. — Will any of your 

 readers be kind enough to inform me where this 

 scale insect is to be found? — H.A. 



