ENGINEERING. 



291 



The adit for draining the Cerro de Pasco 

 silver mines in Peru, which has been in con- 

 struction since October, 1877, is over 400 feet 

 below the surface, and will have a length of 

 2,600 metres, about one half of its course be- 

 ing, it is supposed, through ore-bearing rock. 

 The tunnel is constructed under a contract 

 made by the Peruvian Government with the 

 late Henry Meiggs, by which the latter should 

 receive all the rights of the Government in the 

 mines, and the private owners should at their 

 option relinquish their claims against a royalty 

 of 20 per cent, of the ore extracted, or pay a 

 rent for the use of the tunnel of 30 per cent, 

 of the product. Most of them have assigned 

 over their claims to the builders of the tunnel. 

 The ore-body is said to be one of the great- 

 est, if not the greatest, in the world, and the 

 ore to yield, by the patio process which is in 

 use, from $30 to $40 per ton. The expense of 

 mining it is estimated at not more than $2 per 

 ton. The Trans- Andean Railway, which leads 

 to the mining region, is the highest railway in 

 the world, Cerro de Pasco being 14,200 feet 

 above sea level, and its other terminus, Sacra 

 Familia, 13,700 feet. This mineral road, com- 

 pleted by Meiggs in 1873, conveys the ore seven 

 miles to a water-power which is sufficient to 

 run 1,000 head of stamps. Stamping-mills 

 and hydraulic machinery of great capacity 

 have recently been erected by William H. Cil- 

 ley, who succeeds Mr. Meiggs in the manage- 

 ment. All the parts of the railway and its 

 equipments had to be transported on mule- 

 back from the coast, 200 miles distant, the 

 rails being divided into lengths of six feet. 

 Three iron bridges, two of them of 80 feet 

 span, were transported by the same convey- 

 ance. 



The work on the Hudson River Tunnel was 

 interrupted after the sinking of the circular 

 well 25 feet in diameter and 30 feet deep, with 

 a brick lining three feet thick. Work was 

 again resumed in the autumn of 1878. From 

 this well the boring proceeded ; it was facili- 

 tated by an air-lock, which compressed air 

 into a chamber large enough for three men to 

 work in, having in one corner a funnel into 

 which the excavated material is thrown, and 

 from which it is conveyed to the outside through 

 a long pipe which runs over the mouth of the 

 shaft and empties into a scow ; the force of 

 the compressed air expels the earth and stones 

 through this pipe. The tunnel, as fast as it is 

 built, is lined with a wall of bricks three feet 

 thick, the outer layer of which is of chemically 

 prepared bricks which withstand moisture. 

 The grade of the tunnels is 3 in 100 as it de- 

 scends from the Jersey City side to the distance 

 of two thirds of the width of the river ; it then 

 rises in a gradient of 2 in 100 to its exit in 

 Washington Square. The engineer, Colonel 

 William H. Paine, estimates the entire cost at 

 $10,000,000, and says that two years' work will 

 complete it. 



General John Newton's official report on the 



feasibility of connecting the Hudson and East 

 Rivers by a ship-canal gives as the estimated 

 cost of a navigable channel, 15 feet in depth, 

 $2,777,571 ; the cost of such a channel 12 feet 

 in depth would be $2,270,825. Congress has 

 voted an appropriation of $300,000 for the 

 commencement of the long-talked-of work, and 

 it is expected that the labor will be begun as 

 soon as the Government has secured the right 

 of way from the property-owners along the 

 Harlem River. 



By the opening of the new canal between 

 Aarberg and the lake of Bienne, in Switzer- 

 land, about 74,000 acres of marshy land, which 

 promises a productive soil, have been drained, 

 while the banks of Lakes Morat, Neufchatel, 

 and Bienne are secured against inundation. 

 This canal has been ten years in construction. 



The Chinese Grand Canal, which has been 

 the main artery of internal traffic in the empire 

 for ages, costs so much each year to keep in 

 repair, and is subject to so many stoppages of 

 navigation, that there is serious talk of aban- 

 doning it entirely. If that course is decided 

 upon, there will be a necessity of constructing 

 railroads to supply its place. It is 600 miles 

 long, and is navigated by 10,000 craft engaged 

 in the carrying of grain. 



An important drainage work has been con- 

 structed by Sir John Hawkshaw & Son, in the 

 shape of a sluice to drain the portion of the 

 English fen country called the Middle Level, a 

 tract of 140,000 acres. An old sluice, made by 

 Mr. Walker, gave way in 1862, and was replaced 

 by a series of iron siphons, made to act by the 

 aid of an air-pump worked by a steam-engine. 

 The capacity of these siphons has been found 

 insufficient of late years, for which reason the 

 new sluice has been constructed according to 

 an act of Parliament. It has three openings 

 of 17 feet each, and is capable of discharging 

 280,000,000 cubic feet in a tide, or more than 

 double the amount of drainage which will be 

 required at any time. Each opening is closed 

 by two pairs of gates, so that a second pair can 

 be used in case one should fail. The cost of 

 the whole works, including the six pairs of 

 gates and their machinery, 262,600 cubic yards 

 of excavation, 10,000 cubic yards of concrete, 

 7,268 of brickwork, and 17,000 of ashlar, was 

 a little less than 60,000. 



A work of sanitary engineering of high char- 

 acter has recently been accomplished at Tor- 

 quay. The sewer outlets, which were some 

 little distance out at sea, as is usually the case 

 in marine cities, were liable to be stopped by 

 the action of the tide at certain periods, and 

 the mass of sewage in the lower portions of the 

 sewer to be driven back slightly, thus driving 

 out the sewer-gas at the openings of drains in 

 the town, producing scarlatina and typhoid 

 fever. To prevent such evils, as well as to pre- 

 serve the waters of the Torbay River from any 

 mixture of sewage, a series of tunnels has 

 been made through the surrounding hills ; all 

 the drains are united into one discharging main, 



