Suppose the "Leviathan" steamer running between Liverpool and New-York. She would be occupied ten days at least in receiving her freight, ten days in running and making port or docks, and ten days in discharging. Then, she would be employed only one third of her time in the business for which she was constructed, running; while during two thirds of it she would be acting simply as a pier or dock, over which freight would be handled. Now, with her costly engines, and costly and necessarily idle _employees_, she can not afford to be a dock; neither can she afford to lie still so long. Nor can she on such conditions get the freight necessary to her support. The community on neither side of the water would wish fifteen thousand tons of any class of freights which she could transport dumped down upon the docks at one time. They wish it to arrive a little and a little every day, as it is wanted, just enough to supply the market; and will not lie out of the money which they pay for it, and have it nearly a month in market before they need it, just to have it come on the "Leviathan." It must come along in small lots, just as they need it, and it must be shipped the day that it is bought, and delivered as soon as the ship is in, without being the last lot of fifteen thousand tons, and without keeping the owners so long out of their money. Suppose that A. puts the first lot of freight in at London: he will be the last to receive, it in New-York. A smaller steamer taking another lot two days after, will deliver it before the large ship gets half way over. Or, again, the small steamer may leave London with it when the large steamer has nearly arrived at New-York, and deliver the lot here to the owner in advance. Beside not wishing so large a lot at once, they do not wish it all in one place. The double advantage of a great number of small vessels is, that they bring cargo along as it is wanted, and at the same time distribute it at all of the hundreds of large and small ports, without first delivering it at some great mammoth terminus, and then reshipping and distributing it to its final destination.