The Wealth of Nations by Part 1 Chapter 11 Page 261

shillings. Though its nominal price, therefore, is higher in the present than it was in those ancient times, its real price, the real quantity of subsistence which it will purchase or command, is rather somewhat lower. The price of cow hides, as stated in the above account, is nearly in the common proportion to that of ox hides. That of sheep skins is a good deal above it.

They had probably been sold with the wool. That of calves skins, on the contrary, is greatly below it. In countries where the price of cattle is very low, the calves, which are not intended to be reared in order to keep up the stock, are generally killed very young; as was the case in Scotland twenty or thirty years ago. It saves the milk, which their price would not pay for. Their skins, therefore, are commonly good for little.