280 Origin of Steam- Boats, and [Aprit, 
illustrated. But these are more applicable to the early knowledge 
of that engine than to the present times; and, therefore, we shall 
rather follow him in his description of the mechanism of, his 
steam-boat and engine in the following terms : 
«In some convenient part of the tow-boat, there is placed a 
vessel two-thirds full of water, with the top clogs shut; this 
vessel being kept boiling, rarefies the water into steam; this 
steam being conveyed through a large pipe into a cylindrical 
vessel is there condensed, and makes a vacuum, which causes 
the weight of the atmosphere to press on the vessel, and so 
presses down the piston that is fitted into this cylindrical vessel 
in the same manner as in Newcomen’s engine.” 
“It hath already been demonstrated, that upon a_ vessel 
of 30 inches diameter, which is but 21 feet, when the air is 
drawn out, the atmosphere will press to the weight of 4 tons 
16 ewt. and upwards; therefore, when proper instruments for 
work are applied to it, it must drive a vessel with great force.” 
We have distinctly here the application of the steam-engine 
in 1736 as a propelling power to a vessel afloat, or in other 
words, the discovery of the steam-boat ; and although, as far as 
we know, the inventor confined his views to the navigation 
of rivers and the entrance of harbours, yet it is easy to see how 
it might and has been extended to friths and arms of the sea, 
and may be extended to more distant voyages. : 
We find accordingly that the late Patrick Miller, Esq. of 
Dalswinton, in Scotland, in the course of his various and inge- 
nious investigations into the proper mechanism and sailing of 
ships, coustructed some vessels with double and triple keels, 
to be worked with sails, and also with a steam-engine. By a 
letter from Mr, Miller to Mr. George Salmond, of Glasgow, 
dated Jan. 12, 1814, it appears that Mr. Miller was employed in 
these pursuits prior to the year 1787, when he wrote a treatise, 
of which he presented copies to the following illustrious person- 
ages : to use his own language, “in the first place, to our King, 
also to the late King of France, to the Emperor of Russia, to 
Holland, the Kings of Sweden and Denmark, and other Sove- 
reigns : I also sent copies thereof to the President of America, 
Mr. Washington, to the then Ambassador from America to our 
Court at London, and also to Dr. Franklin. Of this treatise, I 
also sent a copy to the Advocates’ Library, and another to the 
University of Painbarsl and to the Universities of Cambridge 
and Oxford, and the Royal Society at London.” 
Mr. Miller also made various experiments about that time on 
the Forth and Clyde canal, with a boat fitted up with a steam- 
-engine ;* and he mentions, in the letter above alluded to, that 
these experiments succeeded. The late Earl of Stanhope, 
famous as a mechanical philosopher, laboured for years with the 
‘steam-boat at his seat of Chevening, where he afterwards tried 
* The steam-engine in Mr, Miller’s boats was employed to turn a wheel pres 
¢isely as is practised at present in steam-boats, 
