In 1606 the supposition was that the river system of North America might be like that of Russia, where easy portages joining rivers flowing in different directions made it possible to travel, most of the way by boat, from the north to the south of the country and return. "You must observe," advised the adventurers, "whether the river on which you plant doth spring out of mountains or out of lakes; if it be out of any lake, the passage to the other sea will be the more easy, and [it] is like enough that out of the same lake you shall find some spring which runs the contrary way toward the East India Sea; for the great and famous rivers of Volga, Tanis and Dwina have three heads near joynd, and yet the one falleth into the Caspian Sea, the other into the Euxine Sea, and the third into the Polonian Sea." For this information, the Virginia adventurers were indebted to the Muscovy Company, with which Captain Christopher Newport, who commanded the ships dispatched to Virginia, had formerly served. It was a good enough working theory, based partly on knowledge of the geography of Russia and partly on interrogation of the Indians in Carolina by Raleigh's men. And the rivers of that part of North America which lies east of the Mississippi form just such a system as the Virginia adventurers envisaged, except for the fact that the Ohio and other westward flowing streams do not empty into the Pacific. The modern American has usually looked upon such a venture as this as something distinctly apart from an agricultural type of endeavor, but there is good reason for believing that the London adventurers took a different view. They understood the dependence of agriculture upon an opportunity to market its products, and they considered the success of their commercial ventures to be the surest and the quickest way of providing easy access to a market. If a new and practicable route to China could be found in America, any colony located close at hand to the portage along which the goods of the Orient were moved for transshipment to England would find a ready market for food and other provisions by supplying the ships engaged in a highly profitable trade. More than that, the plenty and the regularity of this shipping would provide easy freightage for the encouragement of a variety of agricultural and horticultural experiments looking to the production of such commodities as sugar, ginger, wine, or vegetable dyes and oils. The adventurers well understood the advantage to be gained by duplicating the success previously won by the Portuguese and Spaniards with such experiments in the Azores, in Madeira, in the Canaries, and more recently in the West Indies.