September 19, 1907] 



NA TURE 



527 



As mentioned last week (p. 503), Herr Kritzinger, of 

 Berlin, recently pointed out (^AsUonomischc Nachrichten, 

 No. 4198) that the radiant point of this comet was in 

 346°+!° on September 12. Mr. W. F. Denning informs 

 us that he watched the sky on September 10, 12, and 14, 

 the weather being very clear, but did not notice any 

 meteoric shower from the point mentioned. There was 

 an active radiant at 355° + 5°, however, about ten degrees 

 E.N.E. from the position given by Herr Kritzinger. This 

 display is often seen in September, and there is another 

 at 346°4-i° (exactly agreeing with the cometary radiant), 

 often noticed both in August and September. The corre- 

 spondence in the apparent places is probably accidental. 



Mr. A. J. Hawkes writes from Bournemouth to suggest 

 that the fine sunsets seen on Monday, and also at the 

 end of last week, may be due to meteoritic dust in the 

 track of the comet recently crossed by the earth. 



'The Lowell Expedition to the Andes. — In a recent 

 communication to Dr. W. J. S. Lockycr, Prof. David 

 Todd briefly describes the location and work of the Lowell 

 expedition to the .\ndes for the purpose of observing Mars 

 under the best conditions during the last opposition. Prof. 

 Todd states that he selected Oficina Alianza, in northern 

 Chili, for the location of the Amherst College 18-inch 

 telescope, one of the instruments sent out by Prof. Lowell, 

 and has found the atmospheric condition most favourable. 

 Cloudless skies obtained day and night, and a windlesn 

 and .steady atmosphere produced an average " seeing " of 

 4 on a scale of 5. More than 5000 photographs, covering 

 all regions of the planet, were obtained by Mr. E. C. 

 Slipher, and many of them exhibit clearly the much dis- 

 cussed double canals. The telescope is the last one, of 

 large size, erected by Messrs. Alvan Clark and Sons, and 

 their chief mechanician, Mr. A. G. Use, is a member of 

 the expedition. Photographs of the annular eclipse on 

 July 10 were also secured, and the ringless phase of 

 Saturn was much observed and photographed. Prof. Todd 

 removed the station to a point in the higher Andes above 

 Limas during the first week in August. 



M.1RKINGS ON the Third Satellite of Jupiter. — In 

 No. 4199 of the Aslroiiomische Nachrichten (p. 381, 

 September 6) Senor J. Comas Sold continues his descrip- 

 tion of the markings he has observed on Jupiter's third 

 satellite, and gives position angles determining the posi- 

 tions of the same, at stated times, with regard to the 

 direction of the axis of rotation of the planet. From the 

 discussion of his results he concludes, provisionallv, that 

 (i) the visibility of the northern white cap is independent 

 of the satellite's position in regard to the planet, and is 

 incomparably greater than that of the other cap ; its 

 brightness is comparable to the snow-caps of Mars. 

 (2) .^s on Mars, the northern cap of satellite III. is always 

 bordered by a dark area, which appears darker nearer to 

 the cap. (3) The northern cap appears to be turned 

 towards us, and, if it is situated at the extremity of the 

 axis of rotation of the satellite, the inclination of the 

 equatorial plane to the orbit of the satellite must be con- 

 siderable. (4) The dark spots and areas are difficult to 

 observe, and appear to be variable in a very short time. 

 (5) As yet nothing can be said of the rotation period of 

 the satellite. 



A plate of twelve drawings accompanies the paper, and 

 shows very markedly the different features referred to, and 

 their variations from time to time, as observed during the 

 period November 24, 1906, to March 25, 1907. 



ASTROPHVSICAL OBSERVATIONS AND ANOMALOUS DIS- 

 PERSION.— In Nos. 4197-8 (p. 341, September 2) of the 

 Astronomische Nachrichten, Prof. Hartmann discusses at 

 length the possible explanation of several observed astro- 

 physical phenomena by the theory of anomalous dispersion. 

 He first discusses the general problem, and then its effect 

 in the observed phenomena of the chromosphere, sun-spots, 

 prominences, facula; and flocculi, and the fixed stars. The 

 results of the discussion are not universally conclusive, 

 but Prof. Hartmann points out that, with' stated con- 

 ditions, the question may be decided by special observ- 

 ations. A bibliography of fifty-six papers on this subject 

 is given at the end of the discussion. 



NO. 1977, VOL. 76J 



FORTY YEARS OF CORNISH MINING. 

 IV/r Y connection with Cornish mining began in the year 

 1867, when I succeeded the late Sir Clement (then 

 Dr.) Le Neve Foster as lecturer and assistant secretary to 

 Mr. Robert Hunt's Miners' .Association of Cornwall and 

 Devon. It was a time of transition, for copper-mining 

 after a brilliant career of a century or more was rapidly 

 declining, and tin-mining, which though far more ancient 

 had become second in importance, was once more in the 

 ascendant. The man-engine, the employment of which had 

 been greatly assisted a quarter of a century earlier by 

 substantial prizes offered by the Royal Cornwall Poly- 

 technic Society, was in use in a dozen of the principal 

 mines, wire-rope and skip were gradually replacing chain 

 and kibble, and rock-boring machines, thanks to the 

 initiation of my predecessor, had already been practically 

 tested in several parts of the county. These were real 

 advances, but kibble-winding was still common even in 

 the deepest mines; the cobbing hammer, the bucking iron, 

 the hand-jigger, and the wooden shafted stamp were still 

 at work to a large extent ; while the stonebreaker, the 

 California and pneumatic stamp, the various forms of 

 pulveriser, the Frue and Luhrig vanners, the Wilfley and 

 Buss tables, the self-acting and round slime frames, the 

 air-compressor, and many other contrivances which are 

 now looked upon as essentials in well-provided mines were 

 only beginning to appear. When one compares the present 

 condition of Cornish mining with its condition forty years 

 ago, it is obvious that a sort of revolution has taken place. 



In mining proper there has been no great advancement 

 during the forty years. Somewhat greater depths have 

 been attained in a few instances, and notably at Dolcoath, 

 but Cornwall is still far behind several other mining 

 regions in this respect. We are now more impressed than 

 heretofore with the advantages afforded by good shafts, 

 good underground roads, and good surface transport ; the 

 tramroad and tram-wagon have largely displaced the 

 wheelbarrow ; underground ore-bins, once so rare, are now 

 becoming common ; but in the main our system of under- 

 ground mining was so good even a century ago that there 

 was not very much room for improvement. Still, I will ven- 

 ture to predict that during the next forty years more vertical 

 shafts will be sunk, that levels will be driven farther apart, 

 that there will be a great deal more cross-cutting, and 

 that our underground tramroads will be better constructed, 

 so that " three men at a wagon " will be no more 

 heard of. 



As to the methods employed for breaking the ground, the 

 chief changes have resulted from the use of boring machines 

 and high explosives. In 1S68 I first saw Doering's machine 

 at work in Tincroft Mine. It was not a success, for, being 

 operated by steam, the workings were rendered almost 

 unbearable ; in fact, while steam was the motive power, the 

 use of the machine drill made very little progress either at 

 home or abroad, and it is certain that if compressed air 

 had not been introduced boring machines would to-day 

 play a very small part in mining or tunnelling. Once 

 introduced, however, the immense value of the system was 

 at once recognised. 



The difference between " to-day " and " yesterday " is 

 seen in the fact that no rock-drill or air-compressor has 

 ever been employed in the great mining parish of 

 Gwennap, several of whose mines were still at work a 

 generation ago, while at present all the great mines of the 

 neighbouring parishes of Camborne and Illogan depend 

 very largely upon these machines, not because they break 

 the ground more cheaply, for it is well known that such is 

 not the case (and, moreover, in narrow lodes they do not 

 even break the ground more advantageously, for the " pay- 

 streak " inevitably becomes much contaminated with barren 

 " country "), but because they open the ground more 

 speedily. One good effect of their employment has been 

 the enlargement of the main drifts, and consequent im- 

 proved ventilation, and this has been especially benefited 

 by the large amount of cool exhaust air set free by the 

 machines. The greater number of machine drills hitherto 

 have been employed in sinking, rising, or drifting, but 

 there is a constant and growing tendency to employ them 

 in sloping also. 



Forty years ago much gunpowder was still used in the 



