DESIGNING. 203 



each footing had an imbedded cast-iron washer 30X12^ inches 

 and i inch thick, with a horizontal rib 6 inches deep and i inch 

 thick on its under side. Cylindrical nut seats iyj inches apart 

 were formed in the rib so that two 2|-inch anchor bolts took 

 bearing at the bottom of the rib and extended through it. One 

 pair of diagonally opposite posts were constructed with sliding 

 seats to allow for temperature movements, while the other two 

 posts were bolted rigidly to the foundations. 



Wind-bracing. The effect of the wind upon the water-tower 

 should be provided for by adjustable diagonals secured to ad- 

 jacent columns or horizontal struts near their junctions with 

 the columns. The horizontal component of this stress is taken 

 up by the horizontal struts, while 1 the vertical component of the 

 stress is taken up by the tower-posts, and these latter must be 

 added to the loads to which the posts are subjected. 



These diagonal brace rods act in tension, dependent upon the 

 force and direction of the wind, each alternate set of rods coming 

 into service at the same time. After erection, the tower when 

 subject to its maximum load may become distorted a little through 

 settlement, therefore the rods should be made in two sections 

 and provided with "swivel" or "clevis" nuts to permit of proper 

 adjustment. The design of the rod-connection will depend 

 upon the section of column or strut selected, but where possible, 

 the rod should be bent and welded to form an eye,'' for which 

 a "pin-connection" may be provided. This style of wmd-bracir g 

 is in general use on account of its simplicity and economy, but 

 in the lower tower panel, where a diagonal rod might under 

 certain cases prove objectionable, a type called ''portal-bracing 1 ' 

 might be employed. A most massive, ornamental, and effective 

 example of this type is seen in the lower panel of the Eiffel 

 tower, of Paris. Its general lack of utility for water towers 

 prevents its more frequent use, although its adoption offers con- 

 siderable scope for architectural and ornamental effect. 



Anchorage. The force of the wind acting upon the diametral 

 plane of the tank and the exposed tower surfaces is exerted over 



