. The Locomotive . Table I. Knowing the weight of the engine and the approxi-mate weight of the foundation, it is easy to calculate the area thatthe foundation should cover. In this calculation the weight of con-crete should be taken as 150 lbs. per cubic foot. Table i.^Bearing Power of Soils and Rock. Ledge rock 36 tons per sq. foot Hard pan 8 Gravel 5 Clean sand 4 Dry clay 3 Wet clay 2 Loam I ton The foundation must, of course, be deep enough to be entirelyfree from disturbance by frost. If bed rock can be reached at nottoo great a depth, it would be well to excavate to that depth. Abearing
. The Locomotive . Table I. Knowing the weight of the engine and the approxi-mate weight of the foundation, it is easy to calculate the area thatthe foundation should cover. In this calculation the weight of con-crete should be taken as 150 lbs. per cubic foot. Table i.^Bearing Power of Soils and Rock. Ledge rock 36 tons per sq. foot Hard pan 8 Gravel 5 Clean sand 4 Dry clay 3 Wet clay 2 Loam I ton The foundation must, of course, be deep enough to be entirelyfree from disturbance by frost. If bed rock can be reached at nottoo great a depth, it would be well to excavate to that depth. Abearing on bed rock is not always desirable, however, as will beshown later. In some cases the nature of the soil may be such that the area necessaryto support theweight will not begreat enough tobring the bearingpressure on thesoil within thesafe limit withoutexcavating to anextreme depth. Insuch cases it willbe best to exca-vate to a moder-ate depth andthen to constructa mat, or sub-foundation, asPj(, j shown in Fig. i,. Taylor & Thompson Concrete, Plain and Reinforced. 166 THE LOCOMOTIVE [April, which will distribute the load over a greater area. In any ordinarycase it would probably not be advisable to go deeper than twelve feetto reach a bearing soil, for if an adequate bearing stratum is not reachedwithin this distance it would be better to construct a mat or to sinkpiling and then place the foundation upon a large mat or cap built uponthis piling. This mat should be well reinforced with bar iron. Theregular reinforcing steel is, of course, quite acceptable for this purposealthough a few lengths of railroad iron laid at right angles to eachother is an excellent reinforcement in a construction such as this. Therails should be cleaned of oil and grease before using. There have been installations in which the foundations of thewalls of the buildings have been placed on bed rock and vibration hasdeveloped in the building when the machinery also had its founda-tions resting on this ro
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