1 Jan., 1898.] QUEENSLAND AGRICULTURAL JOURNAL, 13 
SIZE OF TILES. 
Bor lateral drains no smaller than 8-in. tiles should be used, and for open 
soils, where the lines may be placed 100 ft. or more apart, no smaller than 
4-in. tiles should be used. 
The following tables may be used to determine the number of acres which 
a tile of given diameter and per cent. of grade will drain when used as an 
outlet. They are based on Kutter’s formula, and are applicable to main 
drains, well laid, where the water is supplied to them by submains and laterals. 
Table 1 gives the discharge in cubic feet per second for sizes of tile drains from 
4 in. to 20 in. in diameter, computed on a grade of, 1 per cent., or 1 foot per 
100. Table 2 gives the square roots of grades from 0:04 ft. per 100 ft. to 
1 ft. per 100 ft. 
Table 1.—Discharge of tile from 4 in, to 20 in. in diameter on a grade of 
1 ft. to 100 ft. :— 
Diameter of tile in Discharge in eubic feet Diameter of tile in Discharge of cubic feet 
inches. per second. inches. per second, 
4, 016 12 3°40. 
6 “49 15 6°29 
8 11 18 10°37 
9 1:53 20 13°85 
10 2:05 
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Table 2.— Grades per 100 ft., and their square root :— 
Grade per 100ft.] Grade in inches | Square root of | Gradeper 100ft.| Grade in inches | Square root of 
in feet, (approximated). grade. in feet. (approximated), grade. 
04 2 0:200 0:40. 43 0°632 
05 : 224 “AB Be 671 
‘06 3 P45 50 6 “707 
08 £ "283 55 6s 742 
09 1 "300 60 is 775 
“10 12 316 65 7 806 
12 14 346 70 85 837 
14 13 B74 75 9 ‘866 
16 2 “4,00 “80 98 "894, 
‘18 21 *A2A 85 10; 922 
20 Qh “AAT "90 102 ‘949 
25, 3 ‘HOO. 95 Ale “975 
“30 BE 548 1:00 12 1-000 
35 Ax 592 
Oe en ne ep a Teena eee rarer gee ee a A etn, 
‘To determine the number of acres that a tile main of given size.and grade 
will drain, multiply the discharge of the tiles, according to size, as given in 
Table 1, by the square root of the grade which it is proposed to lay the main 
as found in Table 2. When it is proposed that the main shall carry 1 in, in 
depth of water per acre in 24 hours, multiply this result by 24; if 3 in,, multiply 
by 48; if tin., multiply by 96. 
Example :—How many acres will a 12-in. main drain when laid upon a 
grade of 2 in. per 100 ft., using the -in. standard? ‘From Table 1, a 12-in. 
tile on 1 per cent. grade is found to discharge 3-40 cubic feet of water per 
second. From Table 2 the square root of 0:16 ft., or 2 in., isascertained to be 
0-40 ft.; 3:40 x 0:40 x 48= 65°28 acres. The same laid on a grade of 3 in. per 
100 ft. equals $1°6. Tor most of our open soils the 4-in. standard is what is 
used in practice, and is attended with good results. ‘fhis is where drainage 
