We have shown how agriculture was ruined in the Roman empire in Italy, by the free importation of grain from the Lybian and Egyptian provinces of the empire.  As a contrast to that woful progress, the main cause of the destruction of the empire of the Caesars, we request the attention of our readers to the progress of British exports in official value, which indicates their amount from 1790 to 1840, premising that the whole of that period was one of protection to the British agriculturist; during the first twenty years of the period, by the effects of the war—­during the last twenty-five, by the operation of the corn law and sliding scale, introduced in 1814.  We recommend the advocates of free trade to search the annals of the world for a similar instance of progress and prosperity flowing from, or co-existent with, the practical adoption of their principles.

These facts, which, in truth, are altogether decisive of the present question, point to the great source from which the errors of the free trade party are derived, and which appears, in an especial manner, their favourite position, that cheap prices is an unmitigated blessing, and that the great thing to attend to is to increase our imports.  Cheap prices of grain are like the Amreeta cap in Kehama; the greatest of all blessings is the greatest of all curses, according as they arise from magnitude of domestic production, or magnitude of foreign importation.  Of the first we had an example during the five fine years in succession, from 1830 to 1835, during which the foreign importation was practically abolished by the abundant harvests, and consequent high duty on grain under the sliding scale.  This was a period, as all the world knows, of universal and unexampled commercial prosperity.  Of the second we had a memorable example during the five bad years in succession, which elapsed fiom 1836 to 1840, in the course of which the corn laws, from the effect of the same sliding scale, and the continued low prices, were practically abolished; and importations, at the close of the period, amounted to 2,500,000 quarters, and, on an average of the whole, was little short of 2,000,000 of quarters.  And what was the result?  The exportation of 6,000,000 of sovereigns in a single year to buy grain; an unexampled pressure on the money market; commercial embarrassments, long-continued, and severe beyond all former precedent; the contraction of ten millions of additional debt in four years, and the creation of a deficit which at length rose to the formidable amount, in 1842, of L.4,000,000 sterling!  And what first dispelled this distress, and arrested this downward and disastrous progress?  The fine harvests of 1842—­the blessed sun of its long summer, followed by the more checkered, but also fine summer of 1843, which again gave us plenty, derived from domestic production, and consequent general and increasing manufacturing as well as rural prosperity.