Skilful Engineering.

Evening Star, Issue 7484, 31 March 1888, Page 2 (Supplement)

Skilful Engineering.

♦ A skilful piece of engineering has been carried out at the New Croton Aijncduct, which, when completed, is to furnish New York with iin fimplc supply of pure water. A long tunnel had to ho driven. This was done iu lengths, and at the deepest point the shafts by which the tunnel was worked were 350 ft deep and 6,200 ft apart. Starting thus from the foot of two deep shafts at so great a distance from each other, it was a matter of extreme nicety so to drive from cither end that the headings would meet. The slightest deviation even a hair's breadth—to the right or left, up or down, at the beginning of the tunnels would have led to a serious divergence. When the tunnels reached, as waß calculated, within Bft of each other, machine drills were set to work at both ends, the drills being driven in exactly the central lino of the heading. The drills actually met and struck, proving that on both sides the headings had been truly driven. It is doubted whether similar exactness has ever before been obtained in a tunnel of this length. The magnitude of the work may be judged from the fact that the tunnel is 16 miles long, and will take no fewer than 164,000,000 bricks to complete it.