1383 | 1290
30 | 1452 | 1340 | 1244 | 1161
33 | 1320 | 1219 | 1131 | 1056
36 | 1210 | 1117 | 1037 | 968
39 | 1117 | 1031 | 957 | 893
42 | 1037 | 958 | 888 | 829
========================================================================

The following table gives the number of rods per acre of drains at
different distances:

=====================================================================
Intervals between the Drains, in feet. | Rods per acre.
------------------------------------------+--------------------------
15 | 176
18 | 146-2/3
21 | 125-5/7
24 | 110
27 | 97-7/9
30 | 88
33 | 80
36 | 73-1/3
39 | 67-9/13
42 | 62-6/7
=====================================================================

It may be remarked here, that tiles, moulded of the same length, vary
nearly two inches when burned, according to the severity of the heat. It
may be suggested, too, that the length of the tile, in the use of any
machine, is entirely at the option of the maker. It is not, perhaps, an
insult to our common humanity, to suggest to buyers the propriety of
measuring the length as well as calibre of tiles before purchasing. In
the estimates which will be made in this detail, it will be assumed that
tiles will lay one foot each, with allowance for imperfections and
breakage. This is as near as possible to accuracy, according to our best
observation; and, besides, there is convenience in this simple estimate
of one tile to one foot, which is important in practice.

We have now the data from which we may make some tolerably safe
estimates of the cost of drainage. With labor at one dollar per day, and
tiles at $10 per 1,000, or one cent each, or one cent a foot, and
ditches four feet deep, opened and filled at