In the estimates of Mr. Denton, in his tables, collars are set down at about half the cost of the mixed tiles. The bore of them being large enough to receive the end of the tile, increases the price in proportion to the increase in size. It is believed, however, that a smaller size of tiles may prudently be used with collars than without, because the collars keep the tiles perfectly in line, and freely admit water, while they exclude roots, sand, and other obstructions. A drain laid with one and a half inch tiles with collars is, no doubt, better in any soil than two-inch tiles without collars. Some compensation for the cost of collars may thus be found in the less price of the smaller tiles.
6. Laying. The cost of laying tiles is so trifling as hardly to be worth estimating, except to show its insignificance. The estimate, by English engineers, is two cents per rod for "pipe laying and finishing." What is included in "finishing," does not appear. From the personal observations of the writer, it is believed that an active man may lay from 60 to 100 rods of tiles per day, in ditches well prepared. Indeed, we have seen our man James, lay twelve rods of two-inch tiles, in a four-foot ditch, in forty-five minutes, when he was not aware that he was working against time. This is at the rate of sixteen rods an hour, which would give just 160 rods, or a half-mile, in a day of ten hours.
7. Number of Tiles to the Acre. The number of tiles used depends, of course, upon the distances apart of the drains, and upon the length of the tiles used.
The following table gives the number of tiles of various length, per acre, required at different intervals:
| Intervals between the Drains, in feet. | Twelve inch Pipe. | Thirteen inch Pipe. | Fourteen inch Pipe. | Fifteen inch Pipe. |
|---|---|---|---|---|
| 15 | 2904 | 2680 | 2489 | 2323 |
| 18 | 2420 | 2234 | 2074 | 1936 |
| 21 | 2074 | 1915 | 1778 | 1659 |
| 24 | 1815 | 1676 | 1555 | 1452 |
| 27 | 1613 | 1489 | 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 one-third of a day's labor to the rod, we may set down the principal items of the cost of drainage by the rod, as follows:
| Cutting and filling per rod | 33⅓ | cts. |
| Tiles | 16⅔ | " |
| 50 |