The tunnel enters the eastern side of the Hoosac Mountain, in the town of Florida, a few rods from the right bank of the Deerfield River. The eastern summit of the mountain is 2,210 feet above tide-water, 1,499 feet above the Deerfield River, 1,429 feet above the grade of the railroad, and is distant from the East Portal of the tunnel 6,100 feet. The western summit is 2,510 feet above tide-water 1,788 feet above the Hoosac River, 1,718 feet above the grade of the railroad, and 6,700 feet distant from the West Portal. Each portal of the tunnel is 766 feet above tide-water. The summits are 2-41/100 miles distant from each other, and the valley between them at its lowest depression is 801 feet above the grade of the railroad. The length of the tunnel, from the East End to the West End, as commenced by Mr. Haupt, is 4-84/100 miles. Its base is, at the East End, 70 feet above the Deerfield River, and at the West End, 70 feet above the Hoosac River. Its grade, from the East End to the Central Shaft, is 18 feet per mile; from the West End to West Shaft, 26-4/10 feet per mile; and from the West Shaft towards the Central Shaft, 21-12/100 feet per mile. These grades are calculated to allow the free passage of water from the centre. Should the quantity of water found in the tunnel render feasible a reduction of this grade, a change is contemplated. [Illustration: Profile of the Hoosac Mountains] The dimensions of the tunnel areas follows: The rock cutting is 24 feet high and 24 feet wide. The brick-work is 26 feet high and 26 feet wide. The bottom of the tunnel will contain a culvert three feet deep at the centre. Through this culvert the water from the tunnel is to be discharged. It now receives, in addition to the water accumulating in the tunnel, a 12-inch pipe, to carry air at a low pressure for ventilation; an 8-inch pipe to carry air for driving the drilling machines; and a 3-inch pipe for carrying water for use in the holes which are being drilled. Should it be found advisable to use gas in carrying on the work, provision is made for a 4-inch pipe to carry the gas from the place of manufacture. The track is to be placed 3-1/2 feet above the bottom of the rock tunnel, and 4-1/2 feet above the bottom, where lined with brick. The distance by the highway, from the town of North Adams, or from the West End to the East End of the tunnel, is about nine miles. From the first named points to the Central Shaft is about five miles, and from the Central Shaft to the East End the distance is six miles. The time necessary to travel from the West End to the East End, is two hours. Loaded teams from either end to the other perform the distance and return in a day. _Organization of the forces employed in the construction of the Hoosac Tunnel, June, 1866._