Oct.2,i^l2\ 



NATURE 



465 



power. Again, " Hephaistos," says Mr. Gladstone, "bears in 

 Homer the double stamp of a nature power representing the 

 element of fire, and of an autl)ropomorphic deity who is the god 

 of art at a period when the only fine art known was in works of 

 metal produced by the aid of fire." He is also one of the seven 

 star-deities of Chaldxi, the signs and names of which were 

 given at an early date to the seven metals. 



G. F. RODWELL 



THE AMERICAN EXPLORING EXPEDITIONS " 



'T'HE various Government exploring expeditions, the departure 



-^ of which to the fields of operation for the season we have 

 already announced, are biisdy engaged in carrying on the im- 

 portant work entrusted to them ; and it will be safe to expect as 

 the result a larger addition to our stock of detailed information 

 respecting the western regions of America than has ever been 

 brought together during a single year. The most important of 

 these parties are the northwest boundary survey, the geological 

 explorations of Mr. Clarence King along the fortieth parallel, 

 and the surveys of Lieutenant Wheeler in Nevada and Arizona, 

 under the War Department ; that of Prof. Hayden, in two divi- 

 sions, under the Interior Department ; and that of Major Powell 

 in Colorado, under the Smithsonian Institution. 



Perhaps the most thoroughly equipped and elaborate explora- 

 tion is that of Lieutenant Wheeler, which is now fairly in the field, 

 and engaged in carrying on its work. This has for its object a 

 thorough investigation of the region west of the hundredth meri- 

 dian, for the purpose of determining its geographical positions, 

 thoroughly working out its topography, and investigating its 

 geology, natural history, and climatology. 



As the basis of this work, it is proposed by Lieutenant Wheeler 

 to divide the region referred to into eighty-five rectangles of equal 

 size, and to mark their corners with great precision, then, taking 

 each one in detail, to determine its astronomical, physical, and 

 natural histoiy features. This, of course, will require consider- 

 able time for its completion ; and it is hoped that Congress will 

 grant the necessary authority, so that the work may be accomp- 

 lished as speedily as possible. As each rectangle is elaborated, it 

 will, of course, join on to those previously investigated ; and an 

 index map is to be carrie.I along simultaneously for the more 

 ready understanding of the details, liight rectangles have been 

 completed by Lieutenant Wheeler in his previous expeditions, 

 and it is expected that thirteen will be finished by the end oi the 

 season. 



To carry out this programme certain points are to be deter- 

 mined astronomically with great precision, and these as nearly as 

 possible along a continuous parallel. Those already selected are, 

 according to the .\iT;i I'cr/- Herald, a point near Beaunois, near 

 north-western Kansas ; the crossing of the Union Pacific and the 

 western boundary of Nebraska ; Cheyenne ; the eastern limit of 

 the survey of the fortieth parallel by Clarence King ; .Sherman, 

 the highest point on the Union Pacific ; Fort Steele ; Laramie 

 City ; the crossing of the Union Pacific and the western boundary 

 of Wyoming ; the crossing of the Central Pacific and the 120th 

 meridian ; and a point on the western boundary of Nevada. 



Telegraphic determination of the longitude will be used very 

 freely, and for this purpose Brighara Young has kindly permitted 

 the employment of his well-equipped observatory in Great .Salt 

 Lake City. It is proposed to establish a principal station at or 

 near .Sherman, the position of which will lie determined with the 

 utmost accuracy, and to use this as a point of reference for the 

 other stations referred to. The work of the present season will 

 be carried on almost simultaneously in Utah, Arizona, and 

 Nevada, several divisions of the main party having already been 

 organised and set to work. The southern and south-western 

 portions of the Salt Lake basin are to be explored ; also the 

 mining regions on the Virgin and in Eastern Nevada. It is pro- 

 posed to establish astronomical points, by means of which to de- 

 termine with gi^eater accuracy the location of the mineral veins. 

 The Wasatch Mountains will constitute the eastern limit of ope- 

 rations during the year. 



The expedition, as organised, embraces the following among 

 the more important o{\ht personnel : — Lieut. George M. Wheeler, 

 United States Engineers in command ; Lieuts. R. L. Hoxie and 

 W. L. Marshall, U. S. Engineers; Dr. II. C. Yarrow, surgeon 

 and naturalist ; T. \', Brown, hospital steward and meteorologist ; 

 G. K. Gilbert and E. E. Howell, geologists ; J. H. Clark and 



* Conynunicatcd by the scientific Editor of Harper's Weekly. 



E. P. Austin, astronomical obsen'ers ; Louis Nell and John E. 

 Weyss, chief topographers ; H. W. Ilenshaw, assistant natu- 

 ralist ; M. S^ Severance, ethnologist ; and William Bell, photo- 

 grapher. 



At the latest advices the latitude and longitu-!e of Beaver, in 

 Utah, were being determined by Mr. Clark, Mr. Austin being- 

 stationed at the Salt Lake City Observatory. Pioche, in Nevada, 

 will be the next point to be occupied. One branch of the expe- 

 dition, under Lieut. Hoxie, and accompanied by Dr. \'arro\v as 

 naturalist, is exploring the regions west of Great Salt Lake City ; 

 while the other, under Lieutenant Wheeler, is surveying the 

 Wasatch and the Sevier River Iregions east of it. From these 

 main divisions parties are sent out to examine the water-courses 

 and mountain regions of the country traversed. They will all 

 concentrate at Beaver, Utah, about October i, and proceed 

 together toward the south. 



ITALIAN SPECTROSCOPY* 

 "pROF. TACCHINI pre.sented the matter for the fourth issue 

 -•- of the Giornalc ilegli Spettroscopisti, consisting of two 

 memoirs, one by Prof. Blaserna, on the displacement of the 

 lines of the spectrum according to the heat of the prism ; the 

 other, by Prof. Donati, on observations of the spectra of solar 

 spots made at Florence with a new spectroscope. 



The new spectroscope of Prof. Donati contains twenty-five 

 prisms. They are so arranged that the eye receives only Fraun- 

 hofer's line C, and a small portion of the red to the right and left 

 of that line. With this spectroscope Donati has succeeded in 

 seeing clearly the line C reversed on the nucleus of the spots. 

 It does not appear that any of the Italian observers have yet seen 

 the prominences on the disc, a result announced by Lockyer in 

 1869. 



Prof. Tacchini further directed the attention of the Society to 

 his last spectroscopic observations of the sun. For the last few 

 days the number of the protuberances had been rather small, 

 but the chromosphere had been greatly developed, and the 

 vapours of magnesium mixed with it had occupied regions of 

 vast extent. He exhibited a drawing of the spectroscopic 

 image of the Sun's edge, taken on the morning of the 6th of 

 May, 1872, showing the continuous presence of magnesium over 

 an arc of 16S', extending from the north pole to distances of 50" 

 and liS°. Tills was the first time that he had observed a mag- 

 nesium region of such vast extent in the sun. And taking 

 account also of isolated tracts, there results a total of 222', that 

 is to to say, nearly two-thirds of the entire edge, occupied by 

 magnesium vapours more or less intense. The drawing like- 

 wise shows the usual correspondence between the facula;, the 

 magnesium regions, and the portions of the edge at which flames 

 arise to the height of 14 to 28 seconds. 



Lastly, Prof. Tacchini gave an account of some spectroscopic 

 observations maae at Geneva by Prof. E. Gautier, and exhibited 

 the drawings of a protuberance observed by Gautier on the 15th 

 of April of this year, which serve to confirm the observations 

 made at Palermo on the solar rains, that is to say, masses of 

 luminous hydrogen suspended in the sun's atmosphere, which 

 gradually separate, and ultimately unite at the edge of the disc, 

 and then present all the appearance of eruption, whereas their 

 formation actually takes place by a directly opposite process. 



Prof. Blaserna said that he had heard with much interest of 

 Donati's attempt to observe the reversal of the lines on the solar 

 spots. Pie had also, in accordance with the admirable o onfer- 

 ences of Prof. Tacchini in January last, occupied himself with the 

 problem of observing the protuberances on the full solar disc. 

 He then wrote to Prof. Tacchini a detailed letter, proposing 

 two different methods of arriving, if possible, at the solution of 

 this important problem. 



The first of these methods, already applied by Janssen and 

 Lockyer to the protuberances on the solar edge, and now 

 adopted by all spectroscopisls, consists in using spectrosco)ies of 

 continually greater power. Prof. Donati has also pursued this 

 method, and has now arrived at the construction of a spectro- 

 scope of twenty-five prisms. Theoretically, it is highly probable 

 that in this manner the protuberances might ultimately be seen 

 in full sunshine. But for this it would be necessary to go much 

 further with the number of prisms, increasing them to 50, 73, or 

 perhaps even to 100. This, however, involves a great practical 

 difficulty, and, moreover, it is doubtful whether so powerful a 



Societa di Scienze Natural! ed Ecoaomiche di Pale 



May iS, 1872 



