November, 1913. 



KNOWLEDGE. 



433 



are enriched. The greater part of the metallic contents of 

 the upper portion of the ore-body which is being subjected to 

 denudation is carried down in solution, and enriches the 

 lower portion. Many ore-deposits, especially those of copper, 

 are leached near the surface, and are considerably enriched 

 below the leached zone. At still greater depths the ore 

 becomes of lower grade. The zone of enrichment in a mining 

 region is frequently found to have a clear relation to the 

 surface topography, and especially to the ground-water level. 

 The theory of sulphide enrichment has proved of considerable 

 economic importance, and has been applied to many deposits 

 of the metallic sulphides. The subject is of great interest to 

 chemists as well as to geologists, as is shown by the lengthy 

 chemical discussion in the above-mentioned bulletin. 



METEOROLOGY. 



By William Marriott, F.R.Met.Soc. 



FISHERY RESEARCH AND METEOROLOGY.— In 

 the Annual Report on Sea Fisheries for 1912, recently 

 issued by the Board of Agriculture and Fisheries, reference 

 is made to the scientific investigations carried out by the 

 Board. It is stated that although hydrographic data have 

 been collected systematically since 1903, it must be admitted 

 that we are still only beginning to arrive at an understanding 

 of the complicated inter-relations of physical conditions and 

 abundance or dearth of fish. In many cases, however, it has 

 already been possible to trace clear indications of a close 

 connection, not only between hydrographical conditions and 

 the movements of fish, but between these conditions and 

 weather. There is a good reason to believe that changes in 

 the ocean circulation, having a direct effect upon the weather, 

 greatly influence the growth of trees, and the relation between 

 atmospheric and hydrographic conditions is not without 

 interest to the fishing community, both because of the effect 

 of weather conditions upon actual fishing operations and 

 because of wind pressure upon the currents of the sea. It is 

 probable that meteorology has not yet been given its proper 

 place among the numerous sciences which may contribute to 

 the proper understanding of the problems connected with 

 fishing. 



THUNDERSTORMS IN EGYPT— Mr. E. W. Bliss in 

 the Cairo Scientific Journal for June gives some particulars 

 about thunderstorms in Egypt. A list of all available records 

 of thunderstorms for the forty-five years 1868 to 1912 was 

 recently prepared by the Meteorological Service, and a 

 summary made of the results. For the years 1868 to 1903 

 the records depend upon the observations made at Abbasia, 

 but after 1903 they include four storms at Alexandria or else- 

 where which escaped Cairo. The total number of days 

 during the period on which thunderstorms, whether slight or 

 severe, and also cases where lightning only was observed, was 

 one hundred and eighty. The number of thunderstorms 

 which were accompanied by hail or heavy rain, or did damage 

 to buildings, was twenty-eight. It thus appears that there is 

 an average of rather more than one thunderstorm in two 

 years. 



VOLCANIC DUST AND CLIMATIC CHANGES — 

 Professor W. J. Humphreys, of the United States Weather 

 Bureau, in a paper just published in the Bulletin of the 

 Mount Weather Observatory, has dealt with the subject of 

 volcanic dust and other factors in the production of climatic 

 changes and their possible relation to ice ages. Numerous 

 attempts have been made to find a probable cause for the 

 known climatic changes of the distant past, and especially 

 for those profound climate changes that brought about the 

 extensive glaciation that prevailed during the so-called ice 

 ages ; but nearly all the older suggestions have been definitely 

 abandoned because they are inadequate to meet the conditions 

 imposed upon them by the results of geological investigations. 

 Professor Humphreys now puts forward the question of 

 volcanic dust in the upper atmosphere as a factor in the 

 production of climatic changes, including, possibly, even those 

 great changes incident to the advance and retreat to maximum 



and minimum of glaciation. In his discussion of the subject 

 he shows, among many other things, that volcanic dust in the 

 high atmosphere decreases the intensity of solar radiation in 

 the lower atmosphere, and therefore the average temperature 

 of the earth ; and this effect has been clearly traced back to 

 1750, or to the time of the earliest reliable records. It may 

 consequently be said that such a relation between volcanic dust 

 in the upper atmosphere and average temperatures of the lower 

 atmosphere always has obtained, and therefore that volcanic 

 dust must have been a factor, possibly a very important one, 

 in the production of many, perhaps all, past climatic changes, 

 and that through it, at least in part, the world is yet to know 

 many another climatic change in an irregular but well-nigh 

 endless series, usually slight, though always important; but 

 occasionally it may be, as in the past, both profound and 

 disastrous. 



DAILY WEATHER MAPS FOR THE NORTHERN 

 HEMISPHERE. — The Meteorological Committee in their 

 Annual Report state that at the beginning of this year Mr. 

 R. F. Stupart, Director of the Meteorological Service of 

 Canada, brought to their notice specimens of the charts of 

 barometric distribution over practically the whole of the 

 Northern Hemisphere, which are prepared daily in Toronto 

 by co-operation with the Weather Bureau of Washington. 

 The charts in question differ from those now prepared in the 

 Meteorological Office, ten days after date, for issue with the 

 Weekly Weather Report, by including observations from 

 Alaska. These are not charted on the Canadian Daily Chart, 

 which is used for the compilation of the charts in the weekly 

 report, but it is pointed out that they are of exceptional 

 importance in relation to the general distribution of weather 

 conditions. 



The Meteorological Committee are informed that the 

 Russian Government is raising the sum devoted to 

 meteorology to £50,000 a year, with the object, among others, 

 of initiating in the year 1915 a service of strictly simultaneous 

 observations at 6 a.m. and 6 p.m. (Greenwich time) over the 

 whole of the Russian Empire, which extends over nearly 180° 

 of longitude. The extension of the ordinary daily working 

 chart to include practically the whole of the Northern 

 Hemisphere will then be easily realisable. At this moment 

 the cable and wireless companies of the world could exchange 

 information which would give a very fair representation of the 

 weather conditions of the globe to those who are familiar with 

 the average features. The realisation of the project of a 

 " reseau mondial " for the daily weather service is now only a 

 question of international organisation and of money. 



MICROSCOPY. 



By F.R.M.S. 



ANLACODISCUS KITTONII—AK APOLOGY.— As 

 author of the articles in " Knowledge " on " The True 

 Structure of the Diatom Valve," the writer feels an apology is 

 due from him to the editors and readers of this journal. It is 

 due to them for his own lapse by making a claim which he 

 now finds he cannot support, and begs to tender it accordingly. 

 On page 372, Vol. XXXV, two photo-micrographs were repre- 

 sented by him as the first published of Anlacodiscus kittonii, 

 showing the minute details of the structure under an oil- 

 immersion objective of wide aperture. The statement in itself 

 was true enough had the photographs but been of that diatom. 

 Tricked, however, in his memory at the time, he now finds 

 they were not, and his pretension falls to the ground. 



The form then given is still probably a variety. It certainly 

 is about the same size, has the same general features, plus the 

 little bosses, but the cellules are much larger ; neither does 

 the secondary structure offer much difficulty in seeing or 

 photographing. Such a situation renders the writer's position 

 somewhat ridiculous, as he feels that he is bound to redeem 

 his character somehow, and, after assuming the white sheet, 

 now makes the attempt upon a form there can be no mistaking. 



The photo-micrographs of the whole valves, taken for this 

 article, are magnified three hundred and seventy-five times. 

 Looking at the minuteness of the cellules in the two normal 



