which, upon the 16th November 1771, burft its former boundaries, and poured forth a prodigious stream of femi-fluid matter, which, in a fhort time, covered feveral hundred acres of very fine arable ground. Nor will any one, who is acquainted with the nature of mofs,-who knows its resemblance to clay in its quality of absorbing and retaining water, and its very easy diffufibility therein, be surprised at this; as, from all these properties, it is much better adapted for forming an extensive bog; and, therefore, in greater danger of producing an extensive devaftation, by an eruption of the water into it, than those that are formed of any kind of clay whatever.

If the bog, or swampy, ground, is upon a declivity, the ditch ought to be carried across the field about the place where the lowest springs arise. But, if the furface of the ground is level, or nearly fo, as between A and B, (Fig. 24th), and the springs break

out in feveral places, 999999, so as to form foft quagmires interfperfed through the whole of the field, it will be of little confequence in what part the drain is opened; for, if it is dug fo deep as to allow the water to rise in it with freedom, it will iffue through that opening, and the field will be left perfectly dry.

But, as it may frequently happen that the ftratum of gravel fhall be at a confiderable depth beneath the furface of the earth, and as it may be fometimes even below the level of the place into which the drain must be emptied, it might fometimes be extremely difficult to make a ditch fo deep as to reach the bed of fand or gravel. But, it is lucky for us, that this is not abfolutely neceffary in the present cafe; as a drain of two or three feet deep, as at D, will be equally effectual with one that should go to the gravel. All that is neceffary, in this cafe, is, to fink pits (P) in the course of the drain, at a moderate

moderate distance from one another, which

go fo deep as to reach the gravel. For, as the water there meets with no refiftance, it readily flows out at these openings, and is carried off by the drain, without being forced up through the earth; so that the ground is left entirely dry ever after.

I have likewife drained feveral fields in this way; and, as I have generally found the appearances pretty much alike, I fhall, for the information of the inexperienced reader, give a, fhort account of them.

If you attempt to make your pit in one of thefe foft quaggy places where the water is found in great abundance, you will meet with very great difficulty in forming it. For, as the fubftance of which it is compofed is foft, it will always flow into the hole as faft as you dig it. On this account, I would advise, not to attempt to make the pit in the fwaggle, but as near it in the folid earth as you, conveniently can. However, if it is

pretty

pretty firm, and of no great extent, it is fometimes practicable to make a pit in the foft bog, at the drieft time of the year. This I have fometimes practised, which gave me an opportunity of obferving the nature of these bogs more perfectly than I otherwife would have had.

In the trials of this kind that I have made, the foft quaggy ground has feldom been above three or four feet deep, below which I have always found a ftratum of hard tough clay ufually mixed with stones; and fo firm, that nothing but a mattock or pick-axe could penetrate it. And, as this is comparatively fo much drier than the ground above it, an inexperienced operator is very apt to imagine that it is the bottom that he is in fearch of.

In digging through this ftratum, you will frequently meet with fmall fprings 00zing out in all directions. Some of them that might fill the tube of a fall quill,

and

and others so small as to be fcarce perceptible. But, without regarding thefe, you must continue to dig on without intermiffion till you come to the main body of the refervoir, if I may fo call it, that is contained in the rock, gravel, or fand; which you will generally find from two to four feet below the bottom of the swaggle, and which you will be in no danger of miftaking when you come to it. For, if there has been no opening made before that in the field, as foon as you break the cruft immediately above the gravel or rock, the water will burst forth like a torrent, and, on fome occafions, will rife like a jet d'eau, to a confiderable height above the bottom of the ditch; and continue to flow off with great impetuofity for some time, till the pent up water being drained off, the violent boiling up will begin to fubfide, and the ftrength of the current to abate; and, in a fhort time, to flow gently out like any ordinary spring.

Allow