Of the ninety-three inspection warehouses in operation in 1792, only about twenty were above the Fall Line; but by 1820 at least half of the 137 legal inspections were above the Falls. Of the forty-two new inspections established in the period 1800-1820 only three were in Tidewater Virginia; one in Prince George County in 1807, one in Essex County in 1810, and the third in Norfolk County in 1818, owing to the opening of the Dismal Swamp Canal. SALE OF THE LEAF Under the original plan of colonization the Virginia settlers were to pool their goods at the magazine, the general storehouse in Jamestown. All of the products produced by the settlers, and all goods imported into the colony were to be first brought to the magazine. In 1620 the London Company made plans to abolish the magazine and open the trade to the public. The colony was then forced to rely on peripatetic merchant ships which came irregularly. These casual traders dealt directly with the planters, going about from plantation to plantation collecting their cargo. These merchants were without agents in the colonies, and they relied solely upon the chance of selling their goods as they passed the various plantation wharves. They usually sold their goods on credit, expecting to collect their dues in tobacco on the return trip the next year. Occasionally the crops were small, or they discovered that most of the tobacco had been sold or seized by other traders, and consequently they were forced to wait another year to collect from their debtors. The planter soon discovered that he was in an equally precarious situation, and largely at the mercy of the merchant, for if he failed to sell on the terms offered, another ship might not come his way until the following year. The planter's bargaining power was also hampered by his ignorance of market conditions abroad. Such conditions encouraged the practices of engrossing and forestalling, by the merchants, to the point that much legislation was passed to prohibit such actions. Increasing competition by the Dutch traders gradually reduced the dependence of the planter on the casual trading merchant. The danger from pirates and frequent wars caused the English to inaugurate the convoy system, which also helped improve the market conditions. However, trading directly with the casual merchants was still common after 1625, and a few still operated as late as 1700.