The Baltimore Belt Ry. Co. was organized in 1890 by officials of the Baltimore & Ohio, and Western Maryland railways, and Baltimore Capitalists, to build 7 miles of double track railway, mostly within the city limits of Baltimore. This railway was partly open cut and embankment, and partly tunnel, and its object was to afford the companies named facilities for reaching the center of the city with their passengers and freight. To carry out the work the Maryland Construction Co. was organized by the parties interested, and in September, 1890, this company let the contract for construction to Ryan & McDonald of Baltimore, Md. The chief difficulties of the work centered in the construction of the Howard-street tunnel, 8350 ft. long, running underneath the principal business section of the city. =Material Penetrated.=--The soil penetrated by the tunnel was of almost all kinds and consistencies, but was chiefly sand of varying degrees of fineness penetrated by seams of loam, clay, and gravel. Some of the clay was so hard and tough that it could not be removed except by blasting. Rock was also found in a few places. For the most part, however, the work was through soft ground, furnishing more or less water, which necessitated unusual precautions to avoid the settling of the street, and consequent damage to the buildings along the line. A large quantity of water was encountered. Generally this water could be removed by drainage and pumps, and the earth be prevented from washing in by packing the space between the timbering with hay or other materials. At points where the inflow was greatest, and the earth was washed in despite the hay packing, the method was adopted of driving 6-in. perforated pipes into the sides of the excavation, and forcing cement grout through them into the soil to solidify it. These pipes penetrated the ground about 10 ft., and the method proved very efficient in preventing the inflow of water. =Excavation.=--The excavation was carried out according to the German method of tunneling. Bottom side drifts were first driven, and then heightened to the springing line of the roof arch. Next a center top heading was driven, and the haunch sections taken out. The object of beginning the excavations by bottom side drifts, was to drain the soil of the upper part of the section. The center core was removed after the side walls and roof arch were completed, its removal being kept from 50 ft. to 75 ft. to the rear of the advanced heading. The dimensions of the side drifts proper were about 8 × 8 ft., but they were often carried down much below the floor level to secure a solid foundation bed for the side walls.