December 30, 1897] 



NATURE 



205 



metres the diminished pressure is never a direct and sufficient 

 cause of the disorders that are observed, and its only effect is to 

 aggravate those due to fatigue, to impaired digestion, and to other 

 causes. 



Writing in the Memorie della Societa degli speltroscopisti 

 Italiani, xxvi., Dr. G. B. Rizzo publishes the details of a 

 number of observations for determining the value of the solar 

 constant. This value could not be determined with sufficient 

 accuracy from experiments made at one station alone, as it 

 was found that the results varied largely according to the 

 formula employed ; observations should therefore be taken at 

 several stations differing considerably in altitude, but at no great 

 horizontal distance apart. Four stations were therefore selected 

 on Monte Rocciamelone, in the Val di Susa, at altitudes of 501, 

 1722, 2834 and 3537 metres, and by determining the intensity of 

 solar radiation, referred to the zenith, at these stations, the re- 

 lations between this intensity and the corresponding atmospheric 

 pressure were expressed by means of two independent empiric 

 formulae. From these the author finally infers that the solar 

 constant has a value of approximately 2*5 small calories per 

 square centimetre per minute. 



Mr. R. F. Arnott writes to us from Selangor, Straits 

 Settlements, with reference to a note on the alleged conversion 

 of Mexican silver dollars into gold, by Dr. Stephen H. Emmens 

 (September 9, 1897, p. 451). He has assayed four Mexican 

 dollars in circulation at Selangor, and found gold in appreciable 

 quantity, as follows : — 



The dollars were taken at random from rather more than a 

 hundred different issues, and no unusual treatment was em- 

 ployed during assay. The results are worth putting on record, as 

 they suggest a possible origin of the gold in the " argentaurum " 

 manufactured by Dr. Emmens. It is, however, well known that 

 gold exists in Mexican dollars. Our attention has been called 

 to the fact that in 1891 an examination of 11,846 such coins 

 was made at the Royal Mint (see Report of the Deputy- Master 

 of the Mint for 1891, pp. 110-113). The dollars from all the 

 Mexican mints were found to contain gold, the average amount 

 being 0*309 per 1000. Those from Guadalajara (Nos. i, 3 and 

 4 of Mr. Arnott) numbered 463, and contained an average of 

 0'964 of gold per 1000. In connection with the presence of 

 gold in silver, Mr. Arnott points out that much of the silver 

 received at the Indian mints some years ago was rich in gold ; 

 sycee containing an average of about 09 per cent., and silver 

 coins issued contained as much as 0'09 per cent, of gold. 



The attention of the commercial interests of Germany has 

 recently been directed to the great advantage that would be 

 derived to the trade of that country by the completion of the 

 canal system joining the Black Sea with the North Sea, and also 

 with the Baltic. At present all merchandise conveyed to and 

 from the East has to go round by sea to Hamburg or Stettin, 

 the distance by sea being more than 3000 miles as compared 

 with about 1000 miles through Austria and Germany by a system 

 of inland waterways. Two Congresses have recently been held 

 — one at Passau, in Bavaria, and the other at Vienna — for the 

 study and discussion of schemes for developing this through 

 communication, and the Ministry of Commerce at Vienna has 

 had inquiries made as to the feasibility of the plans pro- 

 posed. These are to open out and improve the Ludwig 

 Canal, which connects the Danube with the Main, and so with 

 the Rhine, so as to make it available for barges carrying 500 

 NO. 1470, VOL 57] 



ions, and thus completing a direct water-way between the Black 

 and North Seas. The length of this canal is 106 miles, and it 

 now has a depth of water of only five feet and a navigation fitted 

 for 127-ton barges. The second part of the proposed scheme 

 is to connect the Danube with the Elbe by a new canal from 

 the former, near Vienna, turning in a north-west direction to 

 join the Upper Moldau, and by the canalisation of this river to 

 Prague, and of the Elbe to Aussen. The third scheme is to con- 

 nect the Austrian and German water-ways by connecting the 

 March, an effluent of the Danube, with the Oder, and making 

 the system capable of taking 6c)0-ton barges, and thus connect- 

 ing the Black Sea with the Baltic. The Russian scheme, 

 having a similar object, and described in Nature of February 

 25, is to be commenced forthwith. 



The latest issue of the Memoirs of the Caucasian branch of 

 the Russian Geographical Society (vol. xvii. part i), contains 

 the first part of a very valuable work, by A. V. Voznesensky, 

 on the precipitation in Caucasia. The author gives first a series 

 of tables, for 113 Caucasian stations, showing the amounts of 

 rain and snow, and the numbers of days with rain or snow, for 

 every month of every year during which observations were made 

 at each station. The position of each observatory— its latitude, 

 longitude and altitude, the elevation of the pluviometer above 

 the ground, and general remarks are also given ; and at the 

 end of the work the results are summed up in a general table. 

 Sixteen maps accompany the work : one of them is an oro- 

 graphical map of Caucasia ; then come two series, of five maps 

 each, showing by curves the geographical distribution of pre- 

 cipitation over the territory, i.e. the average amount of pre- 

 cipitation, and the probability of snow or rain for the whole 

 year and for each .season separately. The distribution of pre- 

 cipitation during the different months of the year is next repre- 

 sented by diagrams for thirty stations ; and seven different types 

 having thus been established, the geographical distribution of 

 the regions belonging to each of these types is given on a 

 map. Another map shows the more or less uniformity which 

 exists in the distribution of precipitation during the year in 

 various parts of Caucasia ; and two more maps represent by 

 curves the regions of .summer and winter droughts, as well as 

 the intermediate regions. The text in which the general con- 

 clusions had to be discussed has been left for a second part of 

 the same work, the author having had to leave the Caucasus to 

 take up the management of a meteorological station at Irkutsk. 



It is thirty-five years since the late Mr. S. P. Woodward 

 described the remarkable fossil Barretlia from the Cretaceous 

 limestone of Jamaica. Though in general appearance it re- 

 sembled an operculate coral, Mr. Woodward came to the 

 conclusion that it was really an aberrant Lamellibranch of the 

 Hippurite group. Since that time nothing has been added to 

 our knowledge of the form ; but in a recent Bulletin of the 

 American Museum of Natural History, Mr. R. P. Whitfield 

 gives the results of his study of a large series of specimens 

 obtained from the original locality, which show certain addi- 

 tional details of structure. He cannot agree that Barretlia was 

 a Lamellibranch, but strongly inclines to place it among the 

 corals : it certainly is a very isolated form, as the only corals 

 with which he is able to suggest comparisons in structure are of 

 Palaeozoic age. 



" Do the crystalline gneisses represent portions of the original 

 earth's crust ? " is the question asked, and answered in the 

 affirmative, by Mr. J. Lomas, in his recent presidential address 

 to the Liverpool Geological Society (published in the December 

 Geological Magazine). Excluding gneisses of later igneou ■> or 

 metamorphic origin, there remain the great series of fundamental 

 gneisses, world-wide in distribution and uniform in general 

 character, which must have had some world-wide cause of 



