ENGINEERING. 



249 



chinery, 800 to 900 yards long, and seven feet 

 in diameter. The machines were susceptible 

 of improvement ; yet they were already capa- 

 ble of boring sixty-seven yards in a week, at 

 which rate two galleries, seven feet in diameter, 

 could be made to meet in the middle in five 

 years. From the bottom of the Shakespeare 

 Cliff shaft, 155 feet below the surface, another 

 well was sunk 106 feet deeper, passing through 

 the old gray chalk and into the Gait clay, with- 

 out finding any trace of water. On the French 

 side also two shafts were sunk, and the same 

 favorable results were obtained. The machine 

 with which the tunnel can be bored through 

 the chalk at a much swifter rate than by the 

 ordinary appliances, and which permits the 

 startling project to be entertained as a mercan- 

 tile venture, is the joint property and invention 

 of Captain English, Colonel Beaumont, and Mr. 

 Pigon. The Southeastern Railway Company, 

 which has contributed the funds for the trial- 

 drift on the English side, has agreed with the 

 French projectors that the trial-work should 

 be extended one mile under the channel from 

 each shore, the headings to be of the same sec- 

 tion, seven feet. 



The two main headings of the Severn Tun- 

 nel, which is being constructed under the bed 

 of the Severn by the Great Western Railway 

 Company, were successfully united, September 

 26th, after serious difficulties. Both headings 

 filled with water in 1879. The one on the 

 Monmouthshire side was closed up by masses 

 of the loose sandstone through which it passes. 

 The fragments of rock were driven in by water 

 from the adjacent hills which flooded the works. 

 This heading has been bored 11,000 feet from 

 the bottom of a shaft 180 feet deep, and meets 

 the other with only three inches of deviation, 

 although the vibration of the pumps, which had 

 to be kept constantly going, interfered with the 

 fixing of plumb-lines. The headings are seven 

 feet high and seven feet wide. The tunnel will 

 be enlarged to the width of thirty feet, and to 

 a proportional height. 



The ancient aqueduct built in the time of 

 the Emperor Augustus, to supply Bologna with 

 water, has been restored through the efforts of 

 Count Gozzadini, and was reopened June 5th. 

 The Roman engineers tapped the Setta near its 

 junction with the Reno, about eleven miles 

 from Bologna, and brought the water to the 

 city in a tunnel running along the banks of 

 the Reno, underneath the hills, and under the 

 beds of the torrential mountain-streams which 

 flow into the river. The tunnel was injured 

 only in the places where the streams had worn 

 down their channels, carrying away the mason- 

 ry under their old beds, and where the Reno 

 had washed away its clay banks as far back as 

 the tunnel, taking away portions of the aque- 

 duct. The greater part of the aqueduct, when 

 examined before 1864, was found as good as 

 when first constructed. The masonry was as 

 solid as rock. It was of stone and brick, ce- 

 mented with lime and volcanic sand. The work 



of restoration has occupied many years, and has 

 been executed with a skill and thoroughness 

 calculated to make the new work as firm and 

 durable as the old. 



A method of destroying garbage by fire has 

 been practiced in Leeds, Blackburn, Warrington, 

 Derby, and other English towns, proving emi- 

 nently satisfactory, especially in Leeds, which 

 has led the way in these improvements. At 

 Burmantofts, two miles from the center of the 

 city, a six-celled destructor and a carbonizer 

 were erected. The chambers of the destructor, 

 as it is called, were built in brick, lined with 

 fire-brick, and braced together with iron rods. 

 The destructor occupies a space of twenty-two 

 by twenty -four feet, and is twelve feet in 

 height. An inclined road leads down to the 

 top, and another incline from the level of the 

 firing floor to the public road. Each cell is 

 capable of destroying or carbonizing seven tons 

 of refuse in twenty-four hours. The cells con- 

 sist of a sloping furnace, with hearth and fire- 

 gate covered by a reverberatory arch of fire- 

 brick, with one opening for the admission of 

 refuse, another for the escape of the gases, and 

 a furnace-door for the removal of clinkers. 

 The refuse is emptied on the platform, and 

 shoveled into the cell, falling first on the incline, 

 thence reaching the sloping hearth, whence, 

 when sufficiently dry, it is pushed on to the 

 fire, where, owing to the radiant heat of the 

 firebrick arch, it burns fiercely, the products of 

 combustion being gases, a fine ash, and clinkers. 

 Every cell is provided with an opening large 

 enough to take in infected bedding, diseased 

 meat, etc. The gaseous products of combustion 

 pass through a flue to a boiler, which supplies 

 steam to a horizontal engine driving two mortar- 

 mills. In these mills the clinkers are mixed 

 with lime, and ground into an excellent mortar, 

 which sells readily at five shillings a load ; 

 while the tin cans and iron are sold for old 

 metal. No fuel of any kind is required, the 

 cinders and other combustibles found in the 

 refuse supplying all that is needed. The car- 

 bonizer is used to convert street refuse and 

 vegetable matter into a charcoal, which sells at 

 the rate of thirty shillings a ton. It consists 

 of a group of brick cells, each having a separate 

 furnace. It is twenty-six feet long, twelve feet 

 wide, and fifteen feet six inches high. The 

 chute is fitted with sloping plates, which pro- 

 ject from its sides, and form a kind of spiral 

 ledge, which, near the bottom of the cell, takes 

 the form of a fire-block, resting on a wall which 

 divides the contents of the cell from the gases 

 of the fire. The vegetable and other refuse to 

 be converted into charcoal is filled into this 

 chute in a solid mass, the eaves or ledges form- 

 ing on their under-side a flue, so that the matter 

 is gradually heated as it slips down the well, 

 until, at the bottom, it is surrounded by near- 

 ly red-hot fire-brick. The charcoal is with- 

 drawn at the bottom, and is placed in a cooler 

 worked by the steam-engine, and each cell 

 is capable of treating two tons and a half 



