July 12, 1900] 



NATURE 



263 



paper on the order of crystallisation of silicates in igneous 

 rocks. Referring to a previous communication, the author has 

 extended the observations of the viscous yield of quartz fibres to 

 a temperature of 735° C. Dealing with finely powdered rock- 

 crystal, it is found that this when wrapped in strong platinum 

 foil and exposed for twenty-four hours in a Bunsen flame, shows 

 unmistakable evidence of softening. The powder is loosely 

 caked, and although the great mass is apparently optically 

 unaltered, the particles which have been pressed against the 

 platinum have adhered and melted into blebs, which cannot be 

 removed by friction. Their examination is effected by a 

 vertical illuminator and high power. Finely powdered quartz 

 placed in the meldometer and exposed for four hours to 

 a temperature between 1085° C. and 1070° shows similar evi- 

 dence of fusion. Finely powdered olivine, augite, hornblende 

 and quartz exposed in the meldometer for two and a half hours 

 to a temperature between 1105° C. and 1080° reveal, on subse- 

 quent examination, that the evidence of fusion was conspicuously 

 more apparent in the case of quartz. The experiments were re- 

 peated in an atmosphere of COj. as coloration changes thought 

 to be due to oxidation appear on heating in the case of hornblende 

 and olivine. In CO.^ these changes still appear in less degree. 

 Results otherwise the same as before. The author urges that 

 these results support his view that the softening temperature of 

 the silicates will not be found discordant with the observed normal 

 order of solidification in igneous rocks, but will be found to 

 harmonise with Rosenbusch's law, the depression of the soften- 

 ing point in the scale of temperature being influenced by the 

 amount of silica in combination. On the legitimacy of recent 

 attempts to apply the thermodynamic expression connecting 

 dpjdt with change of volume in reversible systems, the author 

 points out that calculations based on the change of volume of 

 a crystallised silicate to its glass must give erroneous results, 

 and possibly widely erroneous results, seeing that the glass has 

 never existed in the magma at any time, but the crystal 

 was built up from the molecules diffused in the magma. The 

 withdrawal of the molecules from solution may probably have 

 given rise to a volume-change which cannot be ignored. — 

 Mr. S. R. Bennett read a paper containing the results of 

 actinometric observations of the solar eclipse. By exposing an 

 actinometer at intervals of a few minutes throughout the after- 

 noon of the solar eclipse of May 28, it was found that the 

 actinic power of the sun's rays declined rapidly from 2h. 13m. 

 to 3h. 40m. and then increased more rapidly till 4h. 27m. 

 After this there was a regular decrease due to the approach of 

 evening. The exposure at 2h. 13m. was 50s., at 3h. 40m. it 

 was lois. , and 86s. at 4h. 27m. Curves were plotted to 

 represent these results as well as the corresponding ones 

 deducible from theoretical considerations. The curves repre- 

 senting the eclipse effect as found from observation and from 

 theory (on the assumption that the amount of light received 

 from the sun is proportional to the area of his disc exposed) 

 did not agree. That found from observation indicated a greater 

 amount of light received, in the ratio of- 2*3 to i'6 at 3h. 22m., 

 the moment of greatest phase. No satisfactory explanation of 

 this incongruity was given. — Mr. Charles Martin read a paper 

 on heat-radiation observations made at Dunsink Observatory 

 during the eclipse of May 28. 



Edinburgh. 

 Royal Society, June 18.— Dr. Burgess in the chair.— Prof. 

 Copeland and >Ir. Thomas Heath gave descriptions of the 

 preliminary work, the installation of instruments, and the 

 general character of the observations made by them at the 

 recent eclipse. Mr. Heath's communication gave a particular 

 account of the various operations undertaken in connection 

 with the 6-inch Cooke triple object-glass. This object-glass 

 was constructed so as to bring to one focus both the visual and 

 photographic rays. Tested by the most severe tests the instru- 

 ment was perfectly achromatic. Four photographs of the 

 corona were taken during totality on plates 8^ by 6^ inches. 

 Prof. Copeland manipulated the 40-foot telescope which has 

 already done duty on previous occasions. Mr. Frankland 

 Adams had charge of cameras for taking long exposure photo- 

 graphs, and in the working of these had the valuable assistance 

 of officers of H.M S. Theseus. The navigating officer supplied 

 them with time signals ; and by means ot beautiful maps, for 

 which they were indebted to the courtesy of the director of the 

 Madrid Observatory, they were able to determine with great 



ease and accuracy the latitude and longitude of their station 

 near Santa Pola. The Spanish authorities did everything 

 possible to facilitate their operations ; and the members of the 

 expedition experienced nothing but kindness at the hands of the 

 people of the town. Photographs began to be taken 16 seconds 

 before totality, and were continued for 60 seconds after totality. 

 The first contact was observed by Prof. Copeland 10 "2 seconds 

 sooner than the time expected, there being a projecting mountain 

 ridge on the limb of the moon which first moved across the 

 sun's edge. The shadow bands which occur just before and 

 just after totality were observed by some of the men of the 

 Theseus on a vertical wall which had previously been coated 

 with plaster of Paris. — Dr. Buchan and Mr. Omond reported 

 to the Society the nature of the publication of the Ben Nevis 

 observations. For the satisfactory development of meteoro- 

 logical science it was necessary to publish the continuous daily 

 records, and not merely monthly or weekly means. This was 

 now being done with the Ben Nevis observations, both high- 

 level and low-level ; and when the work was completed the 

 meteorologist would be in a position to discuss many problems 

 of the greatest interest and importance. It would require three 

 volumes of the Society's Transactions to complete the publica- 

 tion of the observations on the scale that had been determined 

 upon. To meet the expense of publication, the Royal Society 

 of London had voted 500/. , and an equal grant had been voted 

 by the Royal Society of Edinburgh. 



July 2. — Sir Arthur Mitchell, Vice-President, in the 

 chair. — In a paper on the craniology of the people of India, 

 Part ii, Sir William Turner, F.R.S., described the skulls of 

 the aboriginal hill tribes from the Central Provinces, Chiita, 

 Nagpur, and Orissa. Most of the specimens were in the 

 Indian Museum, Calcutta, but others were in the Anatomical 

 Museum of the University of Edinburgh. They belonged to 

 the so-called Kolarian and Dravidian groups of people. From 

 a comparison of skulls the conclusion was drawn which sup- 

 ported the view advocated by Mr. H. H. Risley from the 

 examination of living persons, that these groups did not differ 

 from each other in physical characters, and that they formed 

 a Dravidian type. A comparison was also made of the 

 Dravidian type of skull with the Australians and the Negritos 

 of the Andaman Islands. Skulls of the Uriya speaking people 

 of Orissa were also described, and the presence of dolicho- 

 cephalic and brachycephalic types, with skulls of intermediate or 

 mesaticephalic proportions, was shown to occur amongst them. 

 —Sir John Murray and Mr. F. P. PuUar communicated the 

 second part of their bathymetrical survey of the fresh-water 

 lochs of Scotland, in which they dealt with Lochs Chon, Ard, 

 Monteith, and Leven of the Forth drainage area, and with 

 Lochs Ericht and Garry in the Tay basin. These lochs differ 

 greatly in elevation, the extremes being : Monteith, 55 feet above 

 the sea; Ericht, 11 52 feet above the sea-level. Their areas 

 vary from 277 acres (Chon) to 4690 acres (Ericht). In this 

 most elevated of the larger lochs of Scotland there are two 

 depressions in which the depth exceeds 300 feet, the maximum 

 depth recorded being 512 feet. The deposits in the deeper 

 parts of all the six lochs consist of a dark brown mud contain- 

 ing much organic matter, but in some there is a second layer, 

 three to six inches beneath the upper layer, of a light brown 

 colour and greater consistency, containing less organic matter. 

 Numerous examples were given of the effect of the wind in 

 driving the warmer surface waters towards the leeward end or 

 side of a loch and in drawing up the colder and deeper layers 

 towards the windward end or side. The shallow lochs were 

 warmer in spring and summer than the deeper lochs, and con- 

 tained more pelagic life. In these discussions it was important 

 to bear in mind the fundamental difference between tempera- 

 ture and amount of heat. It was calculated that the larger 

 lochs with their much smaller change in temperature really 

 stored up more heat than the smaller lochs with their greater 

 change in temperature.— A note by Dr. R. Sydney Marsden 

 was read, drawing attention to a paper he had read in 1880 

 (see Proc. R.S.E., 1881), which contained an account of his 

 method for the artificial preparation of diamonds. M. Henri 

 Moissan, of Paris, described in 1893 ^ method for the prepara- 

 tion of adamantine carbon which differed from Dr. Marsden's 

 method in details which did not seem to be essential. The note 

 was a claim for priority in a matter in which the later experi- 

 menter was now getting all the credit in the eyes of the scientific 

 world. 



NO. 1602, VOL. 62] 



