ENGINEERING. 



379 



slight. It lies 400 feet below the deepest pre- 

 viously existing drainage course in the mines. 

 The rock through which it passes is solid 

 gneiss the whole length, requiring 40 to 50 

 holes to the face with hand-tunneling; the 

 Burleigh compressed-air drill was first em- 

 ployed in 1876. Quicksands and floods of 

 liberated water greatly increased the difficul- 

 ties, and retarded the work. The height of 

 the tunnel is 9.84 feet, and its breadth some- 

 what less. It is ventilated by 8 shafts. The 

 gradient is only 3 in 10,000, so that it will be 

 necessary to clear the tunnel occasionally, 

 which can be easily accomplished with boats 

 and dredges. The work was commenced 

 toward the end of 1844, the surveys having 

 been made the previous year. The entire cost 

 is estimated at 12,000,000 marks, which will 

 be recouped by a levy on the mines benefited. 

 An unknown mine, at least 400 years old, was 

 struck in 1876, in which the timbers were yet 

 sound. Of two new veins discovered, one 

 will be worked. The Freiberg mines and 

 founderies are 700 years old ; and. at the pres- 

 ent time, 6,000 laborers, with their families, 

 depend upon them for support. The point 

 where the tunnel will empty into the Elbe is 

 Kothschonberg, 7 miles above Meissen. The 

 out-turn of the Freiberg mines has fallen off 

 of late years, owing to the constant flooding 

 of the deeper mines. The completion of the 

 tunnel will allow the exploitation of many 

 veins, which could not heretofore be followed 

 down below a certain depth. 



The Severn tunnel, being constructed by the 

 Great Western Railway, to connect Bristol 

 with South Wales, will be 4J miles in length, 

 one-half of it lying under the Severn, not far 

 from the new Severn bridge. The gradient is 

 1 in 100, descending from both ends; and the 

 depth at the lowest level, under the swiftest 



art of the river, is 100 feet below high water, 

 his important work is conducted under the 

 management of Charles Richardson, and is 

 attended with unusual difficulties, owing to 

 the infiltration of water and the varying na- 

 ture of the rock. 



The work of enlarging the Welland Canal to 

 the capacity of the largest lake-vessels will, it 

 is expected, be completed in the autumn of 

 1879. The canal, after the improvement, will 

 have a width of 100 feet at the bottom and a 

 minimum depth of 15 feet, and will be capable 

 of receiving ships of 2,500 tons burden. The 

 locks will be 278 feet long and 45 feet wide, 

 with a depth of 14 feet on the sills. 



Preparations are being made for the con- 

 struction of a ship-canal along the Seine, from 

 Havre to Tancarville a point on the river 60 

 miles below Rouen. It will be in a single sec- 

 tion, 17 miles long, and issuing at the Enre 

 dock in Havre. The plans are for a cutting 25 

 metres broad, with a towing-path of 6 metres 

 breadth on each bank. The bed of the Seine, 

 from Rouen to Paris, is concurrently to be 

 improved, so as to have a minimum depth of 



3.20 metres. The canal will be made 4J- metres 

 deep, and navigable for brigs, schooners, and 

 steam colliers up to Harfleur on the Seine; 

 and above that point it will be given a min- 

 imum depth of 3 metres. The estimates are 

 21,000,000 francs for the canal, a branch 500 

 metres long running up to Harfleur, the plant- 

 ing of trees along the banks, and a basin, 500 

 by 60 metres, at Havre. 



On November 1, 1877, an Inman steamship, 

 drawing 21 feet 8 inches, passed through the 

 jetty at the mouth of the Mississippi without 

 touching. The means of deepening the chan- 

 nel of the South Pass of the Mississippi are not 

 only the jetties, funnel-shaped at their upper 

 end and parallel below, which concentrate the 

 action of the water on the obstructing bars, 

 but also embrace the closing the Grand Bayou 

 and the regulation of the outflow through the 

 Pass 3,.1'Outre and the Southwest Pass. The 

 works for the control of the water in these 

 passes are now in progress. A sill of willow 

 mattresses has been extended across the beds 

 of both passes, from the head of the South Pass 

 to the other side of the river, about 1J mile in 

 length, which is only the foundation of a more 

 complete wicker dam yet to be made. The 

 scouring efficacy of the increased current, and 

 the groundlessness of the fears of a new bar 

 formation, are now assured ; recent surveys 

 show that there is an average increase of depth 

 of 4 feet in an area of 500 feet broad, beyond 

 the mouth of the pass for 1,000 feet out. The 

 amount of the same, from June, 1876, to June, 

 1877, was 1,145,976 cubic yards, or 1 foot 3.7 

 inches over the area mentioned. A broad 

 channel, 24 to 95 feet deep, was running 

 through the jetty at last account ; and there is 

 no doubt that the desired passage of 30 feet 

 depth by 350 breadth will be attained in 

 time. 



The extensive labors carried on by the Ger- 

 man Government in the preparation of the 

 naval station at Kiel are now not far from 

 their completion. The site of the naval estab- 

 lishments, covering 100 morpen, or 53 acres, 

 had to be leveled to a plane 10 feet above the 

 water in the harbor a labor of nine years, in- 

 volving the clearing away of several hills. 

 Two large basins, one 1,700 by 1,200 feet, the 

 other somewhat smaller, and both 66 feet 

 deep, have been dug out, in many places blast- 

 ing having been resorted to. These basins can 

 hold all the men-of-war in the German Navy 

 at one time. The docks, 4 in number, open 

 at their south ends into the smaller basin ; 

 their northern ends are fronted by rows of 

 workshops. The land inclosure is surrounded 

 by a high stone wall. The water-front is pro- 

 tected from the action of the waves by stone 

 walls and groins. 



The Chatham naval docks, in England, are 

 being enlarged by three immense basins, with 

 a total area of 74 acres. Four graving-docks, 

 of enormous capacity, are among the extensive 

 works which are bjeing added to this navy- 



