...leakage of air, from the supply pipes, in a length of one mile and fifteen yards, was only 3%$ °f the head; the absolute initial pressure was 5.70 atmospheres...At the Hoosac Tunnel the air was carried through an 8- inch pipe from the compressors to the heading, a distance of 7,150 feet, operating six drills, with...

....687 .600 5 16.40 3.20O 2.160 1.610 1.290 1. 100 •923 6 19.68 4.446 2.964 2.223 1.778 1.482 1.280 whilst there was an expenditure at the rate of 64...middle of the tunnel, through a length of pipe of, say, 20,000 feet, or 3.80 miles, the absolute pressure only fell from 6 atmospheres to 5. 7 atmospheres,...

...despatch. Compressed Air brakes. Already applied in Paris. Used in sugar refining and chemical works. In the middle of the tunnel, through a length of pipe of about 3| miles, the pressure was reduced, when the perforators were at work, from 6 atmospheres absolute...

...atmospheres, and it was reduced to 5'50 atmospheres, whilst there -was an expenditure at the rate of G4 cubic feet of compressed air per minute. In the middle of the tunnel, through a length of pipe of, say, Velocity at DIAMETER the entnuico to thu Pipe. | 6 Ul 8 PIPE IX 10 INCHES. 12 14 Feet por t-oci.m'1....

....687 .600 5 16.40 3.2OO 2.160 1.610 1.290 I. IOO •923 6 19.68 4-446 2.964 2.223 1.778 1.482 1.280 whilst there was an expenditure at the rate of 64...middle of the tunnel, through a length of pipe of, say, 20,000 feet, or 3.80 miles, the absolute pressure only fell from 6 atmospheres to 5. 7 atmospheres,...

....55 for full pressure and .75 for complete expansion. Hence, substituting these values of E above, we find for these two cases a final efficiency of .27...the heading, a distance of 7,150 feet, operating six drills, with an average .loss of two pounds pressure. CHAPTEE II. THE PHYSICAL PBOPERTIES AND LAWS...

...atmospheres of absolute pressure to 5'8 atmospheres, or to 96f per cent, of the original pressure. In the middle of the tunnel, through a length of pipe of say, 6,100 metres, or 3f miles, the pressure at the surface was reduced, when the perforators were...