212 
Steam Engine. 
one-fourth more to the consumption of fuel, the powers 
of the engine were doubled ; and that twice the quantity 
of fuel required to drive one saw would drive 16 saws, at 
least ; for when I drove two saws the consumption was 8 
bushels (coal) in 12 hours, but when 12 saws were driven, 
the consumption was not more than 10 bushels ; so that 
the more we resist the steam the greater is the effect of the 
engine. On these principles, very light, but powerful 
engines, can be made, suitable for propelling boats and 
land carriages, without the great incumbrance of their 
own weight, as mentioned in Mr. Latrobe'^s demonstra- 
tions. 
In the year 1804, I constructed at my works, situate a 
mile and a half from the water, by order of the board of 
health of the city of Philadelphia, a machine for cleansing 
docks. It consisted of a large flatt, or scow, with a steam 
engine of the power of five horses on board, to work ma= 
chinery to raise the mud into fiatts. This was a fine op- 
portunity to shew the public that my engine could propel 
both land and water carriages, and I resolved to do it. 
When the work was finished, I put wheels under it ; and 
though it was equal in weight to two hundred barrels of 
four^ and the wheels fixed with wooden axletrees, for this 
temporary purpose, in a very rough manner, and with 
great friction, of course, yet with this small engine I trans- 
ported my great burthen to the Schuylkill with ease ; and 
when it was launched in the water, I fixed a paddle wheel 
at the stern, and drove it down the Schuylkill y to the De- 
lawarcy and up the Delaware to the city, leaving all the 
vessels going up behind me, at least, half way ; the wind 
being a- head. 
Some wise men undertook to ridicule my experiment 
of propelling this great weight on land, because the mo- 
tion was too slow to be useful, I silenced them by an- 
e.wering, that I would make a carriage, to be propelled 
