Political Economy. 119 
at every stroke of the piston, such a mass of matter from 
a state of rest to a state of motion, and then irom a state 
of motion to a state of rest. To prevent this loss of pow- 
. er, a light frame of carpentry has been employed by seve-^ 
ral engineers, instead of the solid beam ; but after being 
used for some time, the wood was generally cut by the 
iron bolts, and the frame itself was often instantaneously 
destroyed. In some of the engines lately constructed by 
Mr. Watt, he has formed the great beam of cast iron, and 
while he has thus added to its durability, he has at the 
same time diminished its weight and increased the power 
®f his engine.” 
(To he continued. ) 
POLITICAL ECONOMY. 
The following dissertation by Dr. E.BoLLMANis too good to be 
broken into parts : I publish it therefore together. If any of my 
readers are displeased with discussions on this subject, I am sorry 
for it. I shall hardly be shaken in my opinion, that I can insert 
no subject of a miscellaneous nature so important. T. C. 
VINDICATION OF FOREIGN COMMERCE. 
Dear Sir, 
Agreeable to your permission, and, in discharge of the engage- 
ment which I have in some measure contracted with your readers, 
in consequence of the publicity you were pleased to give to my 
letter of the 16th of June, I am going to communicate to you a few 
remarks in vindication of foreign commerce. I shall endeavour 
to state them, v/ith as much brevity, as the subject will admit of, 
without becoming obscure. 
In all disquisitions on topics of political economy, we should 
constantly keep in mind, as the standard, by a reference to which 
the soundness of every proposition, or maxim, is to be tested^ the 
probable effects of such proposition, or maxim, when put in prac- 
tice., on the productiveness of labour. 
