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method, however, of preparing the bottom of a ditch for tiles is the 

 cutting of a half-circle groove. Only this groove, which is to receive 

 the round tile, needs to be graded with care and absolute exactness, 

 and if the round tile be laid in such a groove the difficulty referred to 

 is not experienced. Whatever the kind of tile selected the individual 

 pieces should be straight, and the ends should be as square and true 

 as possible. The tile should be hard-burned. 



Both glazed and unglazed tile are offered in our markets. The latter, 

 if well burned and of good workmanship, should make excellent 

 drains, but glazing is likely to improve the tile in two directions. It 

 makes the surface over which the water must move smoother, so that 

 friction is reduced, thus giving greater capacity for carrying water for 

 a given size, and the tile must prove somewhat more durable. 



Special Forms of Tiles for Particular Uses. 



There are a number of special forms of tiles for different uses. Among 



the more important are curves, enlarging tiles and junction or branch 



tiles. 



Curves. 



In ordinary land-drainage operations these are seldom necessary, 



but if for any reason the line of the drain must make relatively sharp 



turns, the work is more secure if the turn is made by the use of a curve 



of suitable character. It is a matter of some difficulty to make turns 



in lines of drains with straight tiles, and at the same time make the 



joints between abutting tiles sufficiently close to effectively exclude 



sand and silt. 



Enlarging Tiles. 



The enlarging tile is one that tapers, and such tiles are used when 



on any given line of drain a change is made from a smaller to a larger 



size. 



Junction or Branch Tiles. 



Such tiles are useful in making connections between lateral or branch 



drains and a main drain. Both Y and T branches are manufactured. 



The former are in most cases to be preferred. In order to procure 



when ordering the kind of Y needed the figure designating the diameter 



of the main drain should be placed first and connected by the sign of 



multiplication with the figure indicating the diameter of the lateral or 



branch tile which is to be united with the drain. For example, if a 



2-inch branch is to be connected with a 4-inch main drain the order 



should read " 1 Y, 4 by 2." 



Collars. 



Manufacturers of round tiles usually offer short sections for use at 

 the junctions under the name of collars. Collars are usually about 

 2 or 3 inches long. The collar needed in any case is a short section of 

 tile just large enough to allow the insertion of the abutting ends of the 

 tiles which are being laid. Such collars somewhat increase the security 



