340 
Steam Engine, 
means ; and the steam generated is earned to the place 
intended, by means of tubes connected with the upper 
part of the cylinder A. 
Mr. Woolf has taken out a patent for this ver\" valua- 
ble contrivance. In the specification he has lodged of his 
invention, means are pointed out for applying it to the 
boilers of steam-engines already in use, by ranging a row 
of cylinders below the present boiler, and connecting them 
with each other and with the boiler. Directions are also 
given for constructing boilers composed of cylinders dis- 
posed vertically ; but as w^e consider such an arrangement 
inferior to the horizontal, and as being introduced, per- 
haps, chiefly for the purpose of preventing his patent from 
being infringed by evasion, we shall not give any further 
description of it. We cannot, however, dismiss this ar- 
ticle wdthout quoting some of Mr. Woolf’s remarks^ 
which may prove very useful. 
‘‘ It may not be improper (says he) to call the attention 
of those who may hereafter wish to construct such appa- 
ratus to one circumstance, namely, that in every case the 
tubes composing the boiler should be so combined and 
arranged, and the furnace so constructed, as to make the 
fire, the flame and heated air to act around, over and among 
the tubes, embracing the largest possible quantity of their 
surface. It must be obvious to any one that the tubes 
may be made of any kind of metal ; but I prefer cast iron 
as the most convenient. The size of the tubes may be 
varied : but in every case care should be taken not to make 
their diameter too great ; and it must be remembered, 
that the larger the diameter of any single tube in such a 
boiler the stronger must it be made in proportion, to ena- 
ble it to bear the same expansive force as the smaller cy« 
finders. It is not essential, however, to my invention that 
the tubes should be of different sizes ; but I prefer that 
the upper cylinders, especially the one w-hich I call the 
