[ 316 ] 
TO READERS .-^VARIOUS NOTICES. 
i have been in Philadelphia for a short time, during the print 
ing of this number : hence some inaccuracies of printing, and of 
arrangement have taken place in the present number. Among 
others, I wish the reader to correct in p. 1 69, line 9 from the bottom, 
as follows : for which^ read, to which. In p. If 2, the account of the 
accident from the blowing up of Mr. Trevethick’s engine, is from 
the Philos. Magazine. The account of Mr. Nancarrow*s engine, 
is copied by Nicholson in his 4th quarto volume of his Journal, 
from the transactions of the American Philosophical society. Ill 
p. 218, line 12 from the top, for ufi%vright., read, upright^ and for 
read, preserves. In p. 219, line 3 from the bottom, for 
using as the metalline substances^, read, using metalline substances. 
Some of my finance coirections are not exactly arranged as I could 
wish, but I do not observe any material error. 
While in Philadelphia, I went from thence to Germantown to 
look at an engine of Messrs. Lang and Hauto, constructed with a 
view to economise the force of water, and use streams too small to 
be employed in the common methods of water wheels. The en- 
gine in question, is constructed on the principle of the hydrosta- 
tical paradox, namely, tliat the force of pressure of water, depends 
not upon the quantity, but on the height of the column. Mr. 
Brama, in London, took out a patent some years ago for a packing - 
engine, constructed on this principle, to which also he applied a 
forcing engine in addition to the height of the column. In the 
principle, therefore, there does not appear to me any thing new % 
but in the application of this engine to communicate rotatory mo- 
tion, I think there is great merit. I do not say that this part of 
the machinery is absolutely new, but it is so to me. I shall give a 
description of this engine, which ought to be knov/n ; for the 
principle is capable of converting every house in Front and 
Water streets in Philadelphia, into a manufactory, by the appli- 
cation of the water from the reservoir of the water works. 
During the late dearness of sugar, Mr. PattersoUj 
and my friend Mr. Cloud, of the mint, repeated the experiment 
mentioned in one of my late Emporiums, on the conversion of 
Starch into sugar, with success as to the general result, but not 
as to the cheapness. Oil of vitriol is greatly too dear in this coun- 
try ; in England it sells wholesale for 3^ pence sterling per lb.; 
