_Ventilation._--The subway is ventilated by means of exhaust fans located in seven fan chambers, some of which contain two fans, and others only one fan. Each of the fans has a capacity of from 30,000 to 37,000 cu. ft. of air per minute, and is driven by electric motor, taking current from the trolley wires. This system of ventilation has worked satisfactorily. _Disposal of Rain Water._--The rain water which enters the subway from the inclined entrances, together with that from leakage, is lifted from 12 ft. to 18 ft. by automatic electric pumps to the city sewers. The subway has pump-wells at the Public Garden, at Eliot St., Adams Square, and Haymarket Square. In each of these wells are two vertical submerged centrifugal pumps made entirely of composition metal. In each chamber above, are two electric motors operating the pumps. Each motor is started and stopped according to the height of water by means of a float and an automatic release starting box. The floats are so placed that only one pump is usually brought into use. The other, however, comes into service in case the first pump is out of order or the water enters more rapidly than one pump can dispose of it. In the latter case, both motors continue to run until the same low level has been reached. Very little dampness except from atmospheric condensation is to be found on the interior walls or roof of the subway, although numerous discolored patches, caused by dampness and dust, may be seen on some parts of the walls. Substantially all of the leakage comes through the small drains in the invert leading from hollows left in the side walls. Careful measurement was taken at the end of an unusually wet season to determine the actual amount of leakage, and the total amount for the entire subway was found to be about 81 gallons per minute. _Estimated Quantities._--The estimated quantities of material used in constructing the subway were as follows: Excavation 369,450 cu. yds. Concrete 75,660 „ „ Brick 11,105 „ „ Steel 8,105 tons Granite 2,285 cu. yds. Piles 117,925 lin. ft. Ribbed tiles 12,440 sq. yds. Plaster 88,190 „ „ Waterproofing (asphalt coating) 117,980 „ „ Artificial stone 6,790 „ „ Enameled brick 2,210 „ „ Enameled tiles 2,855 „ „