"4th. The advantage of increased depth, as compensating for increased width between the drains.
"5th. Pipes of an inch bore, the 'best known conduit' for the parallel drains. (See Evidence before Lords' Committee on Entailed Estates, 1845, Q. 67.)
"6th. The cost of draining uniform clays should not exceed £3 per acre."
The most material differences between the views of these two leaders of what have been deemed rival systems of drainage, will be seen to be the following. Smith advocates drains of two to three feet in depth, at from ten to twenty-four feet distances; while Parkes contends for a depth of not less than four feet, with a width between of from twenty-one to fifty feet, the depth in some measure compensating for the increased distance.
Mr. Parkes advocated the use of pipes of one inch bore, which Mr. Smith contemptuously denominated "pencil-cases," and which subsequent experience has shown to be quite too small for prudent use.
The estimate of Mr. Parkes, based, in part, upon his wide distances and small pipes, that drainage might be effected generally in England at a cost of about fifteen dollars per acre, was soon found to be far below the average expense, which is now estimated at nearly double that sum.
The Enclosure Commissioners, after the most careful inquiry, adopted fully the views of Mr. Parkes as to the depth of drains. Mr. Parkes himself, saw occasion to modify his ideas, as to the cost of drainage, upon further investigation of the subject, and fixed his estimates as ranging from $15 to $30 per acre, according to soil and other local circumstances.
It has been well said by a recent English writer, of Mr. Parkes:
"That gentleman's services in the cause of drainage, have been inestimable, and his high reputation will not be affected by any remarks which experience may suggest with reference to details, so long as the philosophical principles he first advanced in support of deep drainage are acknowledged by thinking men. Mr. Parkes' practice in 1854, will be found to differ very considerably from his anticipations of 1845, but the influence of his earlier writings and sayings continues to this day."