TUNNEL 35 autumn of 1872, and the total progress at- tained (two headings) up to Aug. 31, 1875, was as follows : YEARS. By band, yards. By machines, yards. Total, yardi. 1872 182 205 '972 1,951 1,824 5,084 1873 1S74 1S75 The heading is driven at the top, about 8 ft. square, dynamite being used as an explosive. Dubois-Francois perforators were first used, making an average advance of 6'63 lineal feet a day. They were succeeded by Ferroux's, the daily advance being raised to 10-11 ft. Subsequently the machines of two or three inventors, Dubois-Francois, McKean, and Fer- roux, were placed and worked together on the same carriage ; and it is said by M. Louis Sautter, in an official report published in the Revue indmtrielle, Aug. 18, 1875, that the improved McKean drill has proved to be de- cidedly superior to any of its competitors ; its best work on competition, with 6| atmos- pheres of pressure, was a penetration of 12 in. a minute. While actually at work, its rate will vary from 3 to 8 in. a minute, with about 800 strokes. The power is derived from water through the agency of turbines. The cylinders or air pumps of the compressors are 18'1 in. in diameter, and the stroke is limited to 17f in., in order that the mean speed of piston may not exceed 266 ft., or 90 revolutions a minute, the turbine making 390 turns. The compressed air is cooled on Dr. Colladon's system ; every piece that is in contact with the air when un- dergoing compression being cooled by cur- rents of cold water, passed through air-tight envelopes. It is calculated that at the present rates of advance the St. Gothard tunnel may be finished during the summer of 1879, or within seven years from the date of M. Favre's contract. In America, both North and South, many tunnels have been built, the modern ones being mostly driven since the introduction of railroads. Until the building of the Hoosac tunnel in Massachusetts, all tunnelling through rock in the United States was done by hand labor, by the methods above described. The project of tunnelling the Hoosac mountain was broached as early as 1825. In that year a board of commissioners, with Loammi Baldwin as engineer, was appointed to ascertain the prac- ticability of making a canal from Boston to the Hudson, in the vicinity of the junction of the Erie canal with that river. Their report (" Massachusetts Commissioners' Report," 1826, p. 141) declares that " there was no hesitation in deciding in favor of the Deerfield and Hoo- sac river route," and that " there is no hesita- tion therefore in deciding in favor of a tunnel ; but even if its expense should exceed the other mode of passing the mountain, a tunnel is preferable." Railways being shortly after in- troduced, the canal project was dropped. In 1828 surveys were made for three routes to afford Massachusetts railway connection with the west, viz., by Greenfield, by Northampton, and by Springfield. The last or southern route was chosen. The work was not begun imme- diately, but Massachusetts never lost sight of the advantage of a direct route to the Hudson river. This was finally accomplished in 1842, by the completion of the Western railroad to Albany. In 1848 application was made for a charter for a railroad from the terminus of the Vermont and Massachusetts line, at or near Greenfield, through the valley of the Deerfield and Hoosac, to the state line, there to unite with a railroad leading to Troy. The loca- tion was filed in the clerk's office of Franklin and Berkshire counties in November, 1850. In 1854 an act was passed " to enable the Troy and Greenfield railroad company to construct the Hoosac tunnel," by which the state, on certain conditions, lent its credit to the amount of $2,- 000,000. The estimated cost of the proposed double-track tunnel was $1,948,557, and of the road and equipment $1,401,443 ; total, $3,850,- 000. Still the company were unable to raise the funds necessary, in addition to the state loan. In 1855 a contract was made with E. W. Serrel and co., under which some work was done ; and another was made with them in 1856 for the construction of the road and tunnel for $3,500,000, they subscribing $440,000. This contract also fell through, as did one made with H. Haupt and co. in the same year, by which the railroad company agreed to pay $3,880,000 for the completion of the road and tunnel. In 1858 a contract was again made with H. Haupt and co., by which the contract- ors themselves agreed "to assume the labor of collecting subscriptions and of carrying on and completing the Troy and Greenfield rail- road and the Hoosac tunnel." Under this contract H. Haupt and co. were to receive $2,- 000,000 in bonds of the state of Massachusetts, to be exclusively appropriated to work done on the tunnel ; $900,000 in mortgage bonds of the company ; and $1,100,000 in cash, through cash subscriptions and capital stock of the company. Under this contract the work was vigorously prosecuted up to July, 1861, when, a difference arising between the contractors and the state engineer, a certificate for the amount claimed by the former on a payment was refused, and the work was thereupon abandoned by them. In 1862 an act passed the Massachusetts legislature, providing "for the more speedy completion of the Troy and Greenfield railroad and Hoosac tunnel." Un- der this act a board of commissioners was ap- pointed to examine into the matter on the part of the state. At the request of these commissioners, the Troy and Greenfield rail- road company, acting under the authority of certain provisions of the act, surrendered to the commonwealth of Massachusetts, under the several mortgages held by said common-
