May 22, 1879] 



NATURE 



89 



of other works on that order, and Prof. Heinrich Gustav 

 Reichenbach, fils, Director of the Botanic Gardens, Hamburg, 

 alike distinguished for his special knowledge of, and publications 

 on, the Orchidacese, have been elected Foreign Members of the 

 Linnean Society. 



Of eleven female candidates who presented themselves for the 

 first examination for the degrees of London University, six were 

 placed in the division of honours, four were declared to be en- 

 titled to exhibitions, and one was second in the whole list of 

 candidates. There were only two failures. 



Dr. Swan M. Burnett, of Washington, has recently made 

 some examinations for the purpose of ascertaining whether the 

 negro in the United States is affected with colour-blindness to 

 the same degree as the white race. He has examined 3,050 

 coloured children, from six to eighteen years of age, in the 

 public schools of the district of Columbia, of whom 1,359 ^^ere 

 males, and 1,691 females. Of these, twenty-two boys were 

 colour-blind (or i'6 per cent.), and two girls (or o'li per cent.) 

 The percentage of colour-blindness among the whites in an 

 aggregate of about 40,000 examinations is 3 per cent, for males, 

 and 0'26 for females. The negro appears, therefore, to be less 

 liable to this defect than the white race. The examinations were 

 made in strict accordance with the plan proposed by Prof. 

 Holmgren, of Upsala, Sweden, and used so extensively in 

 making similar examinations in Europe. 



A NUMBER of Jablochkofir candles have been employed by the 

 French government, for illuminating, by night, an exhibition 

 held at the ficole des Beaux Arts, for the benefit'of schools. The 

 success is so great, that it has been proposed by M. Turquet, 

 Director of Fine Arts, to open by night the exhibition of 

 Pictures, held now at the Palais de I'Industrie. It is stated that 

 not less than 250 candles will be lighted on this occasion, which 

 will require an engine of more than 300 horse-power. But the 

 expense, although considerable, will be nothing in comparison 

 with the receipts expected. The arrangements will be made 

 during the temporary closing at the end of May, and the electric 

 light be put in operation during the month of June. It is likely 

 that the arrangements will be utilised by the Exhibition of Arts 

 applied to Science, which will be held from July to November. 



The select committee to investigate into the explosion on 

 board Her Majesty's armour-plated turret-ship Thundirer pro- 

 pose to make their experiments in the most public manner, in 

 order fully to establish the stability of the guns constructed on 

 the Woolwich system under all the conditions of the service, 

 and the liability of any gun to be destroyed by unfair means. 

 The burst gun has been taken into the inspection department for 

 examination, and the sister 38-ton gun will be taken to the proof 

 butts in the marshes to be fired. 



The June Sctibner will contain the first of a'series of articles 

 on " Edison and his Inventions," by Mr. Edwin M. Fox. The 

 opening paper will be devoted to the electro-motograph and its 

 applications. The six-years' growth of this remarkable inven- 

 tion will be described by Mr. Fox with much incidental light on 

 the inventor's methods of work. 



The Colonies and India furnishes some interesting particulars 

 respecting the so-called "vegetable ivory," which is now so 

 much used as a substitute for ivory. The vegetable ivory nut is 

 the produce of a species of palm found wild in South America 

 and Africa. Inside the hard shell is the white kernel, which 

 being softer than ivory and easily carved, as well as readily dyed, 

 and being less brittle than bone, is largely used in making 

 buttons, &c. The unripe fruit consists of a green shell, contain- 

 ing a watery fluid, which, as the nut ripens, gradually thickens 

 until it becomes a pulpy mass, and eventually hardens into solid 

 matter. The water, though bitter to the taste, is wholesome, 

 and often renders invaluable service to travellers, who cannot 



otherwise obtain water to drink. The tree {Phytdephas macro- 

 carpa) on which the fruit grows is unlike an ordinary palm, 

 having little or no stem and drooping downwards, especially 

 when the weak branches are overweighted by the six or seven 

 bunches of nuts, each containing six or seven seeds, inclosed in 

 thick heavy shells and outer sheath, and weighing altogether 

 from 20 to 24 lbs. 



A RECENT valuable memoir by Prof. Stefan to the Vienna 

 Academy treats of the relation between radiation of heat and 

 temperature. In the first part he discusses Dulong and Petit's 

 experiments, from which the conclusion was drawn that the 

 amount of heat radiated from a body increases in a geometrical 

 progression, when its temperature increases in an arithmetical. 

 Prof. Stefan points out that the observations of these physicists 

 may be calculated with great approximation by another very 

 simple formula, according to which the amount of heat radiated 

 from a body is proportional to the fourth power of its absolute 

 temperature. It is shown that while the law of geometrical 

 progression corresponds to Dulong and Petit's numbers better 

 than that of the fourth powers, these numbers (because of defects 

 in experiment) are not suited for rigorous proof of the law as to 

 heat radiation. Further, it is shown that the formula of the 

 fourth powers agrees with the observations of Provostaye and 

 Desains much better than that of Dulong and Petit. In the 

 second part of the memoir, cooling experiments are utilised for 

 determination of heat-radiation in absolute measure. In the 

 third it is shown that the formula of the fourth powers agrees 

 fairly well with Draper's experiments on heat radiation of a 

 glowing platinum wire, and Ericson's on that of a glowing block 

 of iron. The fourth part contains some remarks on the suu's 

 temperature. From the intensity of solar radiation as determined 

 by Pouillet, the emissive power of the sun being considered = I, 

 we obtain, according to the formula of the fourth powers, the 

 sun's temperature = 5S8o°' Nearly the same number comes by 

 this formula from Soret's comparative determinations of the 

 radiation of the sun and that of a glowing disk of zirconium. 



A NEW grass, Keana luxurious, has been imported into Ceylon 

 from Java, and is stated to be doing well, having attained a 

 height of 8 feet in three months. It is said to contain a large 

 amount of saccharine matter, and cattle and horses eat it freely. 



Extraordinary finds of gold have lately occurred in the 

 gold-fields of Dutch and French Guiana and are causing great 

 excitement. 



A rich deposit of lead and silver has just been discovered 

 near the Thames River, New Zealand. The ore is reported to 

 contain 50 per cent, of lead, with about two pounds worth of 

 silver, and 9 dwt. 13 grs. of gold per ton. 



According to the Japan papers, a singular innovation has 

 lately taken place in an ancient branch of the trade of the 

 country. Mixadzu, a town in the province of Tanbano-kuni, 

 has always been famous for the manufacture of crape, the 

 principal industry in the province. Hitherto, however, the 

 crape has been manufactured from Japanese silk, but it has 

 recently been discovered that the kind of silk required can be 

 imported from Corea of better quality and much cheaper than 

 it can be procured at home. A number of Japanese merchants 

 have, therefore, formed themselves into a company with the 

 object of manufacturing crape from Corean silk, and have already 

 despatched one of their number to Corea to make the necessary 

 arrangements. 



On Tuesday last week an enormous avalanche descending 

 from the Jungfrau swept through the valley of Stufenstein, 

 carried away a whole forest, and created the utmost consterna- 

 tion in the neighbourhood. So far as is known no lives were 

 lost. 



