3138 Cooper's Rotative Piston. 
minute, and require twenty men to work them. ‘The price 
and power of the other engines do not materially vary from 
the New-York engines. Another defect, or objection, is the 
pair is not inconsiderable. 
Aware of the disadvantages of the engines now in use, 
and desirous of benefitting others, while advancing our own 
interest, we have devoted considerable time and attention in 
constructing fire engines on a principle entirely new. This 
principle was invented by Mr. Cooper, a partner in our con- 
cern, and we have made a number of engines, all of which 
h jualled tsangul pectations, and placed their 
utility beyond the shadow of a doubt. Simple in construc- 
ion, and comparatively light, the expense bears but a sma 
proportion to that of those now in use. Our general rule is to 
them for about one half the price which equal sizes of 
the old ones are sold for; and although our profits at this 
price are not large, we hold it to be the duty of proprietors 
of a patent, where the invention is of great public utility, to 
fix such prices as will enable all to purchase. 
The following is a summary of the advantages claimed by 
the inventors and proprietors for their engine. 
The simplicity of its construction, its rotary motion, its 
admirable compactness and unquestioned durability, are ad- 
vantages, of no slight importance, over those on the old prin- 
ciple, which this machine possesses. Independently of these 
advantages there are others of still greater magnitude. It 
will raise and discharge double the quantity of water, in a 
given time; or, in other words, it requires the application of 
only one half the power, to produce the same effect. It dis- 
charges a more dense column. It is as little affected by the 
frosts of a northern winter as by the heat of summer: an 
it can be made for one half the expense. 
It will raise double the quantity of water. 
The fact is self-evident, that in working the old engines, 
to discharge the chamber or cylinder once, the piston must 
pass twice through it: an ascending stroke to create a va- 
cuum, and a descending one to force the water. Half the 
time is consequently lost. In the rotative, on the contrary, 
it is equally evident, that a continued vacuum is created, and 
