[88] The term horse-power is employed to express the magnitude or capacity and power of an engine. It originated with James Watt from the actual measure of the work which a horse could perform, in raising 33,000 lbs. one foot high per minute; but as any such measure must, in the nature of things, be vague and fluctuating, it was replaced by what is now known as “nominal horse-power,” a mode of measurement based mainly upon the area of the cylinder, the number of strokes per minute and the pressure. But this method is far from showing the actual horse-power, as some modern engines will give an effective power three, four, and even six times greater than the nominal; it serves, however, as a commercial unit of capacity or power of performance and regulates the price to be paid for an engine. But it is much to be regretted that nominal power is not yet estimated by an uniform standard, as different rules are still applied to condensing and non-condensing engines, and these vary in different places.
[89] “Mr. Fulton’s ingenious steamboat, invented with a view to the navigation of the Mississippi, from New Orleans and upwards, sails to-day from the North Run, near States Prison and Albany, the velocity of the steam-boat is calculated at 4 miles an hour. It is said that it will make a progress of two against the current of the Mississippi and, if so, it will certainly be a very valuable acquisition to the commerce of the Western States.”—American Citizen, 17th August, 1807.
[90] “To the Editor of the American Citizen.
“New York, 21st August, 1807.
“Sir,—I arrived this afternoon at 4 o’clock in the steam-boat from Albany. As the success of my experiment gives me great hope that such boats may be rendered of much importance to my country, to prevent erroneous opinions, and give satisfaction to the friends of these useful improvements, you will have the goodness to publish the following facts:
“I left New York on Monday, at 1 o’clock, and arrived in Clermont, the seat of Chancellor Livingston, at 1 o’clock on Tuesday; time, 24 hours; distance, 110 miles; on Wednesday I departed from the Chancellor’s at 8 o’clock in the morning, and arrived at Albany at 5 in the afternoon; distance, 40 miles; time, 8 hours! The sum of this is 150 miles in 32 hours, equal near 5 miles an hour.
“On Thursday, at 9 o’clock in the morning, I left Albany, and arrived at the Chancellor’s at 6 in the evening. I started from thence at 7, and arrived at New York on Friday, at 4 in the afternoon; time, 30 hours; space run through, 150 miles, equal to 5 miles an hour. Throughout the whole way, going and returning, the wind was ahead; no advantage could be drawn from my sails. The whole has therefore been performed by the power of the steam-engine.
“I am, sir, your most obedient,
“Robert Fulton.”
[91] Stuart’s Anecdotes of “Steam-engines,” vol. ii. p. 488.
[92] Fulton’s second large boat on the Hudson was the Car of Neptune. Besides these two vessels he constructed steam ferry-boats to run between New York and New Jersey, also a boat for the navigation of Long Island Sound, as well as others for the Hudson, and for the Ohio and Mississippi.