These bye-ponds will be dispersed about your estate, where perhaps your predecessors thought fit to make them, for the convenience of their pastures, or you may make them as you can best, with respect to charge and other advantages, observing always in a ground to take that part for your pond, to which the waters are most apt to settle. In some places, but very few, the waters stand best upon the hills, and the valleys, when sandy, will not hold well. The nature of the ground is to be regarded.
Some ponds of good depth, of about five or six rods square, should be assigned to maintain pikes, which, when great, ought to be kept by themselves; for in a few years they will devour other fish, and greatly surprise you in the destruction they will make. But I shall speak more of this when I come to the stocking of waters.
I do much approve of cleansing and carting out the mud of small standing waters once in seven or eight years, and so letting them lie dry one summer, if you can spare the water; which, from moats, and pasture-waters, can scarce be done, without great inconvenience. These matters exercise the invention of a good œconomist, who will endeavour to prevent damage, as well as save time, and turn even his pleasures to profit.
One thing I advertise here, which is, not to let carps continue in a small standing water above two summers and one winter; for so you run a much less hazard from frost, than otherwise you will do; besides, the fish will grow much more upon transplanting, than by continuing in the same water, and more in the great, than in the small waters: but of these things more afterwards.
_The Course of laying the Great Waters Dry._
Before I come to the business of fish, I will finish what I had to say about ponds, and the conduct of them; and of that only remains to speak of the course of laying them dry.
As for the smaller waters, I have touched what concerns them already; as for the greater, or principal ponds, proceed thus:
In October, or after, draw the sluice of the first made pond, and lay it as dry as possible you can. It may be the sluice, especially if the pond be many acres, will not vent the water suddenly. That is of no great import, because, as the waters fall, you will have opportunity of fishing with nets, and so clear the fish by degrees; which left to the last, will be too great a burden to clear, and will not be done without damage; besides, the hurry will disorder every thing. If the sluice will not vent all the water from the pan, a labourer or two will soon throw it out with scuppets. Here you find the use of the channels of diversion, spoke of before; for they will keep off all land-waters, if the time should prove rainy, and so permit the pond to empty, and continue dry, which you could not answer for a day without them; and therefore they should be made on both sides of the waters, on each hill one, which will defend the shot of these hills, that otherwise would retard the work.