166. = Steam-Engine—Physics, §c. 
the coal-fire below, where the gas and tar are ignited. The 
fireman judges of the proportion of each, by the effect; the. 
object being to produce a nearly white flame, without appear- 
ance of tar. Thus flame is applied to the greatest possible 
surface, and the apparatus adds very little to the.cost of the 
engine. 
‘There are also two improvements in the boiler, which 1 
deem it important to mention. First, the lining or covering of 
the flue within, with sheet-iron or copper, perforated with 
small holes, reaching down its sides, nearly to the bottom. ’ 
Plate IIL. Fig. 2. athe boiler; 6 the flue; d the grate; cethe 
lining. 
This causes the water to circulate rapidly between them, 
to the top of the flue, and protects it from being run dry, oF 
heated red hot, when the water gets, by accident, tuo low. — 
The lining also, caxses the steam to form much faster, in con = 
sequence of this circulation. ee 
The other is the interior boiler. A vessel occupying the — 
back part of the flue. Plate II. Fig. 8. (d) communicating 
downwards with the water, and upwards with the steam of the 
main boiler. , The fire acts upon it very forcibly, surrounding 
it on all sides. * 
I have said there is no reciprocating movement in Mort $ 
engine. Should it be objected that the piston moves im the 
cylinder as usual, it must be apparent that it also moves Cif 
cularly ; it is in fact the cylinder that moves, carrying the pis- a 
ton with it, which gives and keeps up the motion, by drawing 
and pressing on the centre-piece, and communicating the re 
sistance thence to the guides of the cross-piece on the insides 
of the frame, which thus receives its motion. 
In fact, this form of the engine seems divested of all the 
usual drawbacks on its power, and leaves it to act freely wi 
any velocity, according to the strength of the steam in the 
boilers, . 
+ 
Such it appears in principle, and such thus far in practicé: 
Ihave therefore preferred it for the purposes of navigation 
and have purchased the patent right. But, though interested 
to recommend it, I cannot expect it to be preferred by Y 
