In another section he showed that the cheapness of the staple food of Ireland tended to keep down the rate of wages: “The Irish labourer paid in potatoes has earned perhaps the means of subsistence for double the number of persons that could be supported by an English labourer paid in wheat.... The great quantity of food which land will bear when planted with potatoes, and the consequent cheapness of the labour supported by them, tends rather to raise than to lower the rents of land, and as far as rent goes, to keep up the price of the materials of manufacture and all other sorts of raw produce except potatoes. The indolence and want of skill which usually accompany such a state of things tend further to render all wrought commodities comparatively dear.... The value of the food which the Irish labourer earns above what he and his family consume will go but a very little way in the purchase of clothing, lodging and other conveniences.... In Ireland the money price of labour is not much more than the half of what it is in England.” Lastly, in a passage quoted in the sequel, he showed how disastrous a failure of the crop must needs be when the staple was potatoes; the people then had nothing between them and starvation but the garbage of the fields[464]. What the growth of population could come to on these terms was carefully shown for the district of Strabane, on the borders of Tyrone and Donegal, by Dr Francis Rogan, a writer on the famine and epidemic fever of 1817-18[465]. Strabane stood at the meeting of the rivers Mourne and Fin to form the Foyle; and in the three valleys the land was fertile. All round was an amphitheatre of hills, in the glens of which and among the peat bogs on their sides was an immense population. The farms were small, from ten to thirty acres, a farm of fifty acres being reckoned a large holding. The tendency had been to minute subdivisions of the land, the sons dividing a farm among them on the death of the father: “The Munterloney mountains,” says Rogan, “lie to the south and east of the Strabane Dispensary district. They extend nearly twenty miles, and contain in the numerous glens by which they are intersected so great a population that, except in the most favourable years, the produce of their farms is unequal to their support. In seasons of dearth they procure a considerable part of their food from the more cultivated districts around them; and this, as well as the payment of their rents, is accomplished by the sale of butter, black cattle, and sheep, and by the manufacture of linen cloth and yarn, which they carry on to a considerable extent.”