Eighteenth.—­In this clause you say that in weirs already constructed it shall be lawful for the commissioner, on the application of any two or more persons interested in the fisheries of such river, and at the proper costs and charges of the persons making such application—­proof having been first given, &c.—­to cause a survey to be made of such dam or weir by a competent engineer, and to direct such alterations to be made therein as shall, in the opinion of the commissioner, be necessary and desirable, &c.

In this clause, which so far as it goes is very desirable, you have omitted a proviso without which it could never pass into a law.  You have forgotten to provide for the legal right of the millowner, which would, or might, be taken away by the alteration made in the weir unless there were some provision in the act which prevented this being done.  At present there is no such proviso in your act.  Here I have offered for years to allow the upper proprietors to make any alteration they liked in the weir, provided such alterations did not affect the milling power, the stability of the weir, or my legal title to the weir as existing at present.  And my legal adviser tells me that any alteration made in the weir without a guarantee from the upper proprietors would very probably deprive me of my present title.

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LETTERS ON AGRICULTURAL SUBJECTS.

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ON THE CULTIVATION OF WHEAT ON THE SAME LAND IN SUCCESSIVE YEARS.

To The Editor of the “Manchester Guardian."

CLITHEROE, October 5th, 1843.

SIR,—­I PROMISED to send you some details of my attempt to grow wheat on the same soil year after year.  These I now forward, and hope they may prove interesting.  I was led into these experiments by reading Liebig’s book on the “Chemistry of Agriculture;” for, assuming his theory to be true, it appeared to me to be quite possible to grow wheat on the same land year after year; as, according to that theory, the carbon, oxygen, and hydrogen, which constitute the great bulk of all cereal crops (both grain and straw), are supplied in abundance from the soil and atmosphere (or perhaps, to speak more correctly, from the latter), and we have only to supply those inorganic substances, which, however numerous, form but a small part of the whole weight of the crop.  With the view of testing this theory, and hoping that I might be able to find out what were the elements which built up and cemented the carbon, oxygen, and hydrogen together—­or, in other words, which constituted fertility—­I begun, in the autumn of 1841, to experiment on a field which had been exhausted by a succession of crops, and which had just been cleared of one of oats.  I chose an exhausted field in preference to any other, as the only one in which I could test the truth of the theory.  It was very foul, being full of couch grass and weeds of all kinds.  It was ploughed up and hastily