ENGINEERING. 



331 



ble height above it at the center. Vertical sup- 

 ports connect the roadway with the arches. 

 The longitudinal girders are of double trellis. 

 The principal dimensions are : Span between 

 abutments, 291 feet 4 inches ; rise of arch, 32 

 feet 9f inches ; width of bridge, 37 feet 4| inch- 

 es ; depth of arched girders, 4 feet 7 inches. 

 The carriage - road consists of buckled plates 

 resting on transverse girders, and covered with 

 road-metal, while for the sidewalks checkered 

 plates are used. The iron- work on the bridge 

 weighs 400 tons, and cost $42,000, and the to- 

 tal outlay on the structure was $60,000. The 

 bridge was tested by a uniformly distributed 

 load of 82 pounds to the square foot, deflecting 

 under this strain 1'06 inch. The engineer of 

 the work was M. G. B. Biadego, of Genoa. 



The Arlberg Tunnel. This work was finished 

 in May. It forms a link in the Arlberg Rail- 

 way from Innspruck to Lake Constance, and 

 was undertaken by the Austrian Government 

 to secure more direct communication with 

 Switzerland and western Europe. The road as 

 a whole was one of the most difficult that have 

 ever been built, passing as it does through lofty 

 mountains, with all the usual features of such 

 a route. Snow-sheds had to be built, as on the 

 Central Pacific Railroad, and numerous bridges 

 had to be constructed over ravines of the wild- 

 est character. The length and severity of the 

 winters necessitated placing the line always on 

 the sunny slope of the valleys through which 

 it rims. The tunnel was fully described in the 

 '' Annual " for 1883. An opening was made 

 in November of that year, considerably in ad- 

 vance of contract time, the contractors receiv- 

 ing a premium of $330 a day. A comparison 

 between the times of construction of the four 

 longest rail way -tunnels in the world shows the 

 progress that has been made in methods of con- 

 struction : Hoosac, 4| miles, 22 years under 

 construction; MontCenis, 7f miles, 14 years; 

 St. Gotbard, 9 miles, 9 years ; Arlberg, 6| 

 miles, 5 years. The cost, too, has been reduced 

 from $399 a running foot in the case of the 

 Hoosac, to $154 in that of the Arlberg. 



The Mersey Railway Tunnel, one of the most gi- 

 gantic undertakings of its kind in the world, is 

 approaching completion. The whole work was 

 arched in, and the greater part of the land 

 approaches were finished, early in the year. 

 The whole length of the tunnel from quay to 

 quay is 1,300 yards, and the total length of the 

 railway line will be 4 miles, not including cer- 

 tain contemplated extensions. The termini are 

 the joint stations at Birkenhead of the Lon- 

 don and Northwestern and Great Western lines, 

 and the central station at Liverpool. The land 

 portion is mainly under public streets, with fre- 

 quent stations for the accommodation of pas- 

 sengers. Elaborate hydraulic machinery will 

 be provided for lifting loaded trains, etc., and 

 the contrivances for artificial ventilation are ex- 

 pected to be especially efficient. It is antici- 

 pated that the line will be opened in June, 1886. 



The Nice Water-Works. The city of Nice, 



France, with its 60,000 inhabitants, lies on the 

 shore of the Mediterranean, surrounded by a 

 belt of steep hills, the Maritime Alps, whose 

 slopes, wherever practicable, are made to serve 

 for what we term truck- farming, olive-rais- 

 ing, floriculture, and the like; and the mag- 

 nitude of the interests involved, taken in con- 

 nection with the water-supply of the city itself, 

 has been for a long time a serious problem. 

 The natural water-supply, which is excessive 

 during a few weeks, falls off almost to nothing 

 during the rest of the year, and it is only by 

 dint of laborious effort and the strictest econ- 

 omy that the suburban residents have managed 

 to exist. The constant growth of the city and 

 the rapidly increasing number of foreign resi- 

 dents of late years rendered the necessity of 

 a greater supply still more imperative, and in 

 1878 a company was organized to construct an 

 irrigating canal from the Vesubie, the princi- 

 pal tributary of the river Yar, to the valley of 

 the Paillon, which runs through the streets of 

 Nice itself, forming a sometimes dangerous tor- 

 rent in the rainy season, and remaining nearly 

 dry the rest of the year. The Romans appear 

 to have struggled with a similar problem centu- 

 ries ago, and the remains of their aqueducts can 

 still be traced along the hill-sides. The state 

 agreed to pay the company a trifling subsidy of 

 about $480,000, and no more under any circum- 

 stances. The rest of the responsibility was as- 

 sumed by the Oompagnie Generate des Eaux, 

 with the privilege in perpetuity of charging 

 for the use of its water. 



The main canal, recently completed, has a 

 capacity of 141 cubic feet a second, and is 

 subdivided into three branches each, and an 

 overflow to flush the ordinarily dry bed of the 

 Paillon. Besides, two water-mains with a joint 

 capacity of 60,000 metres a day are laid for 

 9J miles along the two banks of the Paillon, 

 and the city is to pay $16,000 a year for the 

 water thus furnished. Water was delivered 

 in the city early in the present year, and the 

 work of completing the irrigating canals and 

 the water-main on the east bank is rapidly pro- 

 gressing. The main canal follows the right 

 bank of the Yesubie for a mile, then crosses 

 to the left bank by a bridge of 46 -foot span, 

 crosses six other smaller bridges, and passes 

 through 64 tunnels before it reaches the Saint 

 Blaise siphon, 10^- miles from the opening. 

 This siphon is U-shaped, with the sides in- 

 clined and the base flat. It consists of four 

 rows of cast-iron pipes placed parallel to each 

 other. The major horizontal span is 1,480 

 feet, and the bridge on which the horizontal 

 portion is carried is 164*5 feet long. The total 

 length of the siphon is 1,677 feet; the vertical 

 height is 393 feet 8 inches, equaling a maxi- 

 mum pressure of 12 atmospheres. The inter- 

 nal diameter of the pipes is 31'5 inches, and 

 the total discharge is S,170,000 gallons an 

 hour. Beyond the siphon the canal contin- 

 ues for 8*7 miles, passing over 14 bridges and 

 through 21 tunnels, aggregating over three 



