230 TOWEKS AND TANKS FOR WATER-WORKS. 



estimated as making a cubic yard of masonry, which weighs 

 approximately 1.2 tons. With such brick an ordinary mason, 

 with one helper, will lay 2000 in foundations. In such work, 

 below the surface, the brick can be rapidly placed in courses 

 and then grouted in by "slushing" cement-mortar over the 

 surface, which fills the interstices and makes a bed for the 

 succeeding course; in such foundations bats may be used in 

 moderate numbers. At the ground-line more care is taken, 

 and the brick are laid to a horizontal line, those forming the 

 face being carefully laid, and the mortar-joints, which should 

 not be over ^ in. thick, are " struck" and neatly pointed. A 

 good foundation-brick should be of close clay texture, well 

 made, hard, and carefully burned. When two such brick are 

 struck smartly together they should give a clear, metallic ring. 

 Foundation-brick should not absorb more than about 7 per 

 cent, of their weight of water after immersion for 24 hours. 

 The color of a brick is no index of its qualities, although 

 where the clay soil contains oxide of iron the color of the 

 brick after burning will be red, and a good foundation-brick 

 will be a "cherry-red." Obviously, the bearing- value of 

 brick varies with the texture of the material, its care in 

 making and burning, and the skill with which it is erected 

 into masonry when bonded with a suitable mortar. As shown 

 by table, page 158, the safe bearing-value of brick masonry, 

 in cement-mortar, is taken at from 8 to 10 tons per square 

 foot, and experience has shown this to be a safe and conserva- 

 tive value. Numerous tests have been made upon piers 

 erected under different conditions by the United States gov- 

 ernment and individuals, but it is doubtful whether such 

 experiments are of much practical value. 



While in no wise conclusive, the failure of a brick f>ier 

 and the collapse and total destruction of a tower and tank 

 designed by the author, gives an opportunity to present cer- 

 tain facts in that connection which may assist in throwing 



