510 



NATURE 



[April 2,, 1^79 



The cost per metre would thus have been 87fl. 86kr., and j 

 indeed such was the case in the first eleven years ; but 

 after the French revolution the value of money was 

 greatly changed, and the prices became so high, that in 

 the next thirty-three years very little was done, the yearly 

 progress not being more than 6i '4 metres, and the cost 

 per metre 371 A- Szkr. 



From 1826 the works were carried on with greater 

 energy at the cost of 26ofl. 4okr. per metre till 1835, when 

 the progress again became slow, and remained so for the 

 next eighteen years, only seventy-two metres being worked 

 yearly, at the cost of 3i3fl. 45kr. per metre. 



But after the middle of the present century the sense of 

 the decline of the mines from their former state of pros- 

 perity was so prevalent, that the director of the district, 

 M. Russegger, well known on account of his scientific 

 travels in Europe, Asia, and Africa, proposed that they 

 should again devote greater energy to the works in 

 question, as most of the mines were under water, and 

 the raising of this by machines caused an outlay which 

 the mines were not able to bear. For the next twelve 

 years the yearly progress was 293*2 metres, at the cost of 

 237fl. 63kr. per metre. During the next five years after 

 Russegger' s time only 141 "i metres were worked out 

 yearly. 



The Hungarian government has through the last ten 

 years again developed greater activity in this work, and 

 the parliament has at its request granted the yearly sum 

 of 100,000 florins for the purpose. 



In the year 1874 there were still 2,326 metres to be 

 woikod niit, which would under ordinary circumstances 

 have been a task of eleven years ; but in 1873 experi- 

 ments were made in boring with machines, which method 

 was tried for the first time in the Mont Cenis tunnel, with 

 surprising success, then in the St. Gothard railway tunnel, 

 and lastly in the " Sutro" gallery (Nevada). After many 

 trials they succeeded in finding out the most convenient 

 arrangement, and the whole work was done in three and 

 a half years. With this method the entire tunnel could 

 have been finished in 27 years. 

 The length of the Mont Cenis tunnel is ... 12,233 metres. 



„ „ St. Gothard is 14,920 metres. 



„ „ Sutro gallery of mines is 6, '47 "metres. 



„ „ Joseph II. Adit is ... 16,538 metres. 



The total cost amounts to 4,599,000 florins. 



The importance of this tunnel is very great, firstly as 

 regards geology. The geological and orographical litera- 

 ture of that country is very old ; Schemnitz has been 

 repeatedly visited by distinguished men of science from 

 all quarters of Europe, but the difficulties and complica- 

 tions of its geological structure are so great that there is 

 still much to be done. One of the greatest obstacles in 

 the way of investigation is that the surface is very 

 seldom well exposed ; dense forests and products of 

 decomposition of the rocks cover many of the slopes. 

 The tunnel furnishes a section more than ten miles in 

 length, and gives not only valuable information as to the 

 downward prolongation of the lodes known in the upper 

 levels, but some new ones have been traversed, and the 

 entire series of rocks, with their mutual hmits as well as 

 modifications and occasional transitions is to be seen 

 without interruption. 



It is important secondly as regards mining. A new 

 region has been made accessible, and the master-lodes can 

 now be worked to their full extent, while in past years 

 all activity was absorbed by the unlucrative Adit itself. 

 Now the works again promise a long continuance. All 

 the machines used in raising the waters are put away, and 

 thence an outlay of more than 100,000 florins is saved 

 yearly. 



The last and not least advantage consists in enriching 

 the miner with new means of working. The application 

 of mechanical boring may be considered as forming for 

 him a new era, just as did the introduction of gunpowder ; 



Declination Log distance Log. distance 

 North. from Karth. from Sun. 



9-9789 



97767 



he will now much more easily undertake the driving of 

 adit-levels, whenever this is feasible, and so, it is to be 

 hoped, that the neighbouring old mining cities will suc- 

 cessively have their galleries of efflux too, which is the 

 essential condition of the restoration of their prosperity 

 in mining. 



OUR ASTRONOMICAL COLUMN 



Brorsen's Comet. — From an observation at Krems- 

 munster by Prof. Strasser on March 14, it appears that 

 this comet has passed its perihelion several hours later 

 than the time calculated by Dr. Schulze of Dobeln, the 

 corrections to the ephemeris on that date being — 31s. 

 in right ascension and — 3'*5 in declination ; yet observa- 

 tions at Rome on February 17 and at Arcetri, Florence, 

 on March 10, give different corrections. For the present, 

 as the ephemeris is sufficiently near for finding the comet, 

 the following positions and distances may be extracted 

 from it : — 



oh. Berlin Right 



M.T. Ascension. 



h. m. s. o ' 



April 4 ... 2 55 29 ... 25 44 



„ 5 ... 2 59 16 ... 26 59 



„ 6 ... 3 3 5 ... 28 15 ... 9*9663 ... 97824 



,, 7 ... 3 6 58 ... 29 32 



„ 8 ... 3 10 55 ... 30 49 ... 9*9538 •■• 97898 



„ 9 ... 3 14 56 ... 32 7 



„ 10 ... 3 19 2 ... 33 25 ... 9*9415 ••• 9*7986 



,, II ... 3 23 13 ... 34 44 



„ 12 ... 3 27 31 ... 36 2 ... 9-9295 ... 9-8086 



,, 13 ... 3 31 58 ... 37 22 



„ 14 ... 3 36 32 ... 38 41 ... 9-9179 ... 9-8196 

 On March 10 Dr. Tempel estimated the comet brighter 

 than a star of the eighth magnitude, the theoretical in- 

 tensity of light at the time being 1-18 ; the maximum 

 value attained this year is 3*33 on April 14, and during 

 the latter half of April and the whole of May the comet 

 will no doubt be well observed ; from April 14 to June 10 

 it will be constantly above the horizon of Greenwich. At 

 its next return in 1884, its apparent track in the heavens 

 is not likely to be a favourable one for observation, and 

 as long a course of observation as is practicable at the 

 present appearance will be desirable for carrying forward 

 the elements of the orbit to 1890. 



MiRA Cetl — In 1879 and 1^8° the minima of this 

 variable occur at times when the star will be too near the 

 sun to be observable, but the maxima, according to Arge- 

 lander' s formula of sines, take place under very favour- 

 able circumstances for accurate determination, in 1879 on 

 September 11, and in 1880 on August 1 1. From the ob- 

 servations of Dr. Julius Schmidt at Athens, it appears 

 that this formula, which had given the epochs of maxi- 

 mum in 1876 and 1877 (two) earlier than the observed 

 times by 17-7, 16-8, and 19-4 days respectively, was only 

 in error in this direction four days in 1878. 



Among variable stars now favourably situated for ob- 

 servation, may be mentioned Lalande 23617 and 23726, 

 the former has been rated from 6m. to 9m., and the latter 

 from 5m. to 8m. Also Lalande 26211, which has been 

 noted as high as 6ni. and as low as 9m. ; the variation, 

 however, appears less decided in this case, though Bessel 

 estimated the star 8m. ; Lalande' s 9m. may perhaps be 

 considered a misprint, as there are known to be similar 

 cases in the " Histoire Celeste." 



The Minor Planet Hilda.— A new determination 

 of the orbit of this, the most distant member of the minor 

 planet group, by Kiihnert, of Vienna, assigns a period of 

 revolution of 2,861 days, or 7-832 years, and an aphelion 

 distance of 4-52 ; at this point of its orbit the planet is 

 distant from the orbit of Jupiter only 0-85, so that con- 

 siderable perturbations are possible. The search for 

 Hilda at the present opposition, so far as we know, has 

 been unsuccessful. 



