Democratic Sentinel, Volume 15, Number 36, Rensselaer, Jasper County, 25 September 1891 — THROUGH TO CANADA. [ARTICLE+ILLUSTRATION]

THROUGH TO CANADA.

THE BIQ TUNNEL IS NOW COMPLETE. Elaborate Dedicatory Exercises at Both Ends of the Subterranean Passageway—A Hole in, the Ground Six Thousand Feet Long—How the Work Was Accomplished. The St. Clair Tunnel. The ceremonies by which the St. Clair River tunnel was formally dedicated were the most elaborate of any ever held in that section. Extensive preparations had been made both at Port Huron, Mic'.i., on the American side, and at the town of Sarnia, at the Canadian entrance to the great tunnei which now connects the Dominion with Uncle Sam’s domains Sir Henry Tyler, President of the Grand Trunk Railway, with other officia's and prominent public men of both the United States and Canada, made an oflßcai trip through the tunnel, starting from the American side. They were treated, upon their arrival in Canada, to a royal reception, after which they returned to Port Huron, where banqueting and speech-making again awa'ted them. The St. Clair tunnei, on the Trunk Railway of Canada, extending under the St. Clair River between Sarnia, Ont, and Port Huron, Mich., is ono

of the most remarkable engineering feats of the present day The Gtand Trunk Railway extended its lines to Chicago in 1880. About 5,000 miles of railway will use this tunnel. Previously steam ferries had been used Their service has not been altogether satisfactory because the river s current is very swift; in winter there have been ice jams; the railway had to deviate about six miles; abridge was impossible, owing to the nature of the ground and the opposition of the marine interests. The St. Clair River bears the most commerce of any stream in ?ho world. In 1884 preliminary surveys were made. Borings found the rock elghty-

six feet below the leva! of the water; the river’s greatest depth 40.47 feet* and its width nearly half a mile. The strata were yellow sand about two feet; with sand and blue clay mixed about twelve feet, thence to the rock about twentyone feet of blue cay. Plans and drawings were made. The St. Clair Tunnel Company was organized in 1886. At first the company thought of starting from immense shafts on the shore, and then working outward to the land approaches. In 1886 test shafts were sunk on each side of the St Clair Riveig drifts at right angles were started under the liver; water and gas stopped work. In 1887 these shafts were begun. The American one will be used as a ventilator. The tunnel plants were erected back from the river; In Michigan about 1,800 feet, in Ontario about 1,900 feet. Each plant contained a boiler house, hoisting or winding engines, a ventilating en-

gine, an a;r-tlower with a capacity of 10,000 cubic feet of air per minute, a machine shop with machines for tunnel work, a -water pump for the pit, and an electric light plant. The tunnel will be lighted by electricity. The electric plant Is in Sarnia, where permanent brick boiler and engine rooms have been ; erectedThe great enttings for the approaches were commenced New Year's, 1889. Each cutting was made about sixty.feet feet deep at t e po'rta'. The Canadian cutting at its broadest portion is 260 feet wide, the American about 200 feet wide. Into each pit inclined tracks were laid, for engines to haul out the dirt On the* banks derricks were erected for hoisting the soil. In September. 1890, steam shovels began work on the cuttings. On each side of # the river two shove’s wefe used, each attended by an engine and train of flatcars. Several hundred men were employed night and day, lime lights being used at night, and the soli was removed in layers. The work of the;e shovels was greatly hindered by rainsand nuraeious landslides occurred. r lhe tunnel wails are made of cast Iron, suggested by Chief Engineer Hobson. In the circle are thirteen segments and a key. Each segment is 4 feet 10 inches long. 18 inches wide, and 2 inches thick, with flaeges inside of 1% Inches thick and 6 inches deep. In each segment were cast 32 holes. 4 in each end flange and l£>in each side flange. Through these holes passed steel bolts seven eighths of an inch in diameter In each section of the tunnel the circular joints required 157 bolts and

the longitudinal joints required 56 belts. The flanges took in a circle of 29 feet and 5 inches in diameter. The edges of the plates were planed in the machineshops near the tunnel entrances Each plate was then heated and dipped in cold tar. This had been found better than to dip the cold iron into hot tar. Formerly the tar would not dry quick enough; later the tar was dried by the time the segments were cool. The segments were ilf ted to place by a circu ar crane revolving on a spindle in the center of the shield. This spindle had a vise at one end and a counterbalance weight at the other. When the bed of the river was reached, quicksand and water made great trouble. For some time it was thought the tunnel might ha\e to be abandoned. Compressed air was found a sure remedy. At the river line on each side, brick and cement, air-tight bulkheads were built across the tunnel. Each bulkhead had two air chambers, one on each side. 7 feet in diameter and 17 feet long, with air-tight doors at each end. Through each air chamber passed a car track. Inside the tunnel, beyond the bulkhead, work was begun under an air pressure of 10 pounds to'the square inch. Fiom time to time the air pressure was gradually increased, until the men worked under an artificial pressure of 23 pounds per square inch, a total atmospheric pressure of 37 pounds per square inch, or about 2>4 atmospheres. On the Canadian side the highest air pressure was used becafuse of quicksand. On the American side compressed air was used from April 7, 1890; on the Canadian, May 20, 1890.

. Because of water and quicksand the £>t Clair tunnel could not have been constructed without lhe,aidof hydraulic mining shields. Such shields had been used successfully in London, Chicago, Buffalo, Broadway tunnel, Kew York City, the Hudson River tunnel, and in other works. This shield is a cylinder, iike a headless barrel. Its .front end has sharpened edges to cut into the earth. The thin rear end‘is called the hood. The in ido is braced with iron, both vertical and horizontal. Around the main walls are sets of hydraulic jacks. Each jackbas a valve whereby it may bo cut off at any time fr6m the pump that supplies; the jack. The masonry, or iron plates, of the tunnel, being built up withitxthe thin hood of the shield, air is supplied to the jacks and the shield is forced ahead, usually the length of the pistons of tho jacks, or about two feet. The shield having advanced the men remove the soil from the front of the shield. Everything being in readiness the shield is again pushed so. ward, the walls built up, and the excavated soil removed. Each of- the St. Clair tunnel shields weighed eighty tons. The American shield was started July 11, 1889, the Canadia Sept 21, «1889, and they met at 11:30 p. m., August 3J, 1890.

The shields’ shells wore left in the tuntunnel and the tunnel walls laid up In them. The American had done the most work, and the easiest progress was toward Canada, the average being ten feet each day. The tunnel approaches have the same general appearance of solidity as the tunnel itself. On each side of the groat cutings are high and deep stone retaining walls. Each aortal is 36 feet high and 148 feet wide*, about 10 feet thick over the entrance of the tunnel, and about half that width at each end. Like the retaining walls the portals are made of rough, heavy limestone blocks. Over the entrance of each portal Is inscribed “St. Clair, 1890.” The diameter of the circle is 20 feet, and flush with the tunnel. The average number of men employed was 700. In the tunnel eight hours made a day’s work. The tunnel was estimated to cost $2,500,000, including

plants, materials and labor, and It required abput that sum. It is likely that a second tunnel will be built bear this. The present plants and experience will then be of additional value. The Second tunnel will be of cast iron, as It Is superior to brick and cement for similar tnnnels. The St Clair tunnel is 6,000 feet long. To the river’s edge on the American side It Is 1,716.1eet; on the Canadian, 1.904 feet; under the river, 2,290 feet. The out ide diameter of the tunnel is 21 feet, the inside 19 feet 10 inches, tunnel nearest the river ifrß.43 feet from the river. At its lowest point the top of the tunnel is 56.83 feet below tb® level of the river. From each portal to the r ver the grade is 1 foot down for every 50 feet; under the river, 1 foot down in every 1,000 feet toward the Canadian side to that drainage shafts Over 2,000,000 cubic feet of soil was taken from the tnnnel itself. The castiron lining o* the tunnel weighed 54,000,000 pounds. To fasten th s lining 828,150 steel bolts seven-eighths of an Inch in diameter ®rere ffsed. The Canadian open cutting is 3,193 feet long; the American, 2,532 feet long. The total length of the tunnel and its approaches i 5,11,725 feetc* It is believed that the Grand Trunk route, as thus improved, will offer facilities for through t ommunication between Chicago and all points in the East^which will be appreciated by pas-engers and shippers. There will be no more trouble from ice bio ks or other obstructions in the river and the best time will be made , for traffic of all kinds.

ENTRANCE TO THE TUNNEL.

MEETING OF THE SHIELDS IN THE BIG BORE UNDER THE RIVER.

A SHIELD READY" FOR THE GRADE.