│ │ │ │ │ │ │ 12 │ ¼ │ 5/16 │ ⅜ │ ⅛ │ ¼ │ 1/16 │ 2 │ │ │ │ │ │ │ 15 │ ¼ │ 5/16 │ ⅜ │ ⅛ │ ¼ │ 3/32 │ 3 │ │ │ │ │ │ │ 18 │ ¼ │ ⅜ │ 7/16 │ 3/16 │ ¼ │ 3/32 │ 3 │ │ │ │ │ │ │ 21 │ ¼ │ 7/16 │ ½ │ 3/16 │ ¼ │ ⅛ │ 3 │ │ │ │ │ │ │ 24 │ ⅜ │ ½ │ 9/16 │ ¼ │ ¼ │ ⅛ │ 4 │ │ │ │ │ │ │ 27 │ ⅜ │ ⅝ │11/16 │ ¼ │ ¼ │ ⅛ │ 4 30 │ ⅜ │ ⅝ │11/16 │ ¼ │ ¼ │ ⅛ │ 4 33 │ ⅜ │ ¾ │13/16 │ ¼ │ ¼ │ 3/16 │ 5 36 │ ⅜ │ ¾ │13/16 │ ⅜ │ ¼ │ 3/16 │ 5 39 │ ⅜ │ ¾ │13/16 │ ⅜ │ ¼ │ 3/16 │ 5 42 │ ⅜ │ ¾ │13/16 │ ⅜ │ ¼ │ 3/16 │ 5 ─────────┴───────┴──────┴──────┴────────┴───────┴─────────┴──────── NOTE 1. For methods of making tests see Proc. Am. Soc. for Testing Materials. NOTE 2. Concentrated load at end of vertical diameter. (_a_) Slants shall have their spigot ends cut at an angle of approximately 45 degrees with the longitudinal axis. (_b_) Curves shall be at angles of 90, 45, 22½, and 11¼ degrees as required. They shall conform substantially to the curvature specified. (_c_) ... All branches shall terminate in sockets. [Illustration: FIG. 73.—Standard Clay Pipe Specials. Courtesy, Blackmer and Post Manufacturing Co. ] In Fig. 73 are shown the various forms of vitrified pipe and specials which are ordinarily available on the market. The life of vitrified clay sewers and some observations on the results of the inspection of the sewers in Manhattan are discussed in Chapter XII. The strength of vitrified sewer pipes is shown in Table 37. TABLE 37 STRENGTH OF SEWER PIPE