GO NOTES ON pi.\Ti:-',ii;i>r.i: m-:sn;\ 



allowed to slide on a plate. This arrangement makes the 



mination of the reactions |o<>ible. 



The area of the bearing on the wall, assuming the bridge 

 seats to be of granite and 600 Ibs. per square inch as a 



unit stress, should l>e ' -323 sq.in. 



It is not advisable to make an end bearing of the simple 

 nature indicated in Fig. 12 too long. Tin tendency of 



FIG. 12. 



such a bearing is to overstress the bearing along its inner 

 edge. 



The upper plate of the two shown at each end is 

 called the sole plate, and is connected by rivets, counter- 

 sunk on the bottom, to the girder. The bottom of tin- 

 sole plate at (6), the expansion end, should be planed. 



