The paddle-wheels were of a primitive form, and as they were unprovided with paddle-boxes, the arrangement had the appearance of a great undershot mill-wheel on each side of the boat, above the deck of which was placed the steam-engine, a position it has retained in all these river-boats, in which a huge, rhombus-shaped beam, oscillating high above the deck, is a conspicuous feature. Another boat of much larger dimensions was built the following year, having a tonnage of nearly 300, and from that time there has been a more or less regular increase in the sizes of the vessels, until in 1866 a tonnage of nearly 3,000 was reached. In 1817 a vessel called the _Livingstone_ was launched, which was able to go up to Albany in eighteen hours. In 1823 was launched the _James Kent_, a novel feature in which vessel was the boiler made of copper, and weighing upwards of 30 tons. It was so planned that if it happened to burst, the hot water would be carried through the bottom of the vessel by tubes or hollow pillars. From this it appears that considerable apprehension existed as to the liability of the boilers exploding. We are told that the cost of the copper boiler was in this case nearly one-third of that of the whole vessel. The cabins are described as having been very handsomely fitted up, and the speed was such that fourteen hours sufficed for the trip up river to Albany. Many fine boats were placed on the river during the twenty following years, and these were marked by various improvements, as when, in 1840, anthracite coal was for the first time substituted for wood as the fuel for the furnaces, with the effect of reducing the cost of this item to one-half. Then, in 1844, iron began to be used for constructing the hulls, and a few years afterwards, steamers having a speed of twenty miles an hour and over, became quite common. In 1865, and again in the eighties, some four screw-propeller boats were built; but this type does not appear to have found much favour on the Hudson, for the large paddle-wheels and the single or double beam, working high above the deck, have continued the almost universal form of construction. A very popular and famous boat was placed on the Hudson in 1861. This was the _Mary Powell_, called the “Queen of the Hudson,” which, although a boat of moderate tonnage (983), was able on occasion to steam at the rate of twenty-five miles an hour. This vessel was placed on the line between New York and Rondont, and was still running in 1894.