There are, we know, many people who, in spite of all the testimony which has been adduced, and the solemn declaration of the farmers that they cannot carry on cultivation at present prices, refuse to believe that the agricultural interest is virtually doomed to extinction. They say that the farmers are habitual grumblers, and they insinuate that this may be a false alarm. Now, as to grumbling, we suspect it would be impossible to find any body of men, who are exposed to constant fluctuations in the value of their produce, exempt from such a propensity; and we have heard, ere now, something worse than grumbling proceed from the throats of the manufacturers. But we ask those gentlemen whether, supposing America were to carry her avowed purpose into execution, and to stimulate her own population by converting the raw material of cotton into fabrics, instead of sending it four thousand miles across the Atlantic to be spun in Manchester,—and supposing that, in consequence, American calicoes could be offered in the British market at a price lower than the cost of the production of a similar article would be to Mr Cobden or Mr Bright—they imagine that the machinery of Manchester, Rochdale, and Staley Bridge, would still continue in motion? Does not common sense—does not all experience tell us, that a losing trade must be abandoned? And in order to show that agriculture is a losing trade, we need have recourse neither to farmers’ statistics nor to pamphlets, however valuable. We prove it out of the mouths of our adversaries. Here they are:— SIR ROBERT PEEL, in February 1842, estimated the proper remunerative price of wheat in this country, “allowing for natural oscillations,” as between 54s. and 58s.—on the average, 56s.; and stated, that he, “for one, would never wish to see it vary beyond these two specified values.” Mr JAMES WILSON, M.P. for Westbury, writing in 1839, stated it as his opinion, that the proper price of wheat was 52s. 2d.; and that, whatever average annual price the farmer received in any year less than that standard price, he made “so much distinct loss.” Sir CHARLES WOOD, Chancellor of the Exchequer, stated in January 1850, that he did not think “the agriculturist would be ruined with wheat at 44s. a quarter.” THE AVERAGE PRICE OF WHEAT AT THE HADDINGTON MARKET, ON 8TH FEBRUARY, WAS 34S. 1D. We know, moreover, that sales of good wheat have been made in Scotland, since that time, at even lower prices.