1822.] 
2. Strength of the Vessel. 
The regularity, speed, and safety, 
with which the Holyhead steam-hoats 
crossed the Tvish channel, throughout 
the whole of last winter, are the best 
evidence of the vast importance of 
great strength in the construction of 
this description of vessels. Captain 
Rogers says, that he would rather be 
in a steam-boat, in the heaviest gale 
that could blow, than in a sailing- 
packet, if constructed like the Holy- 
bead steam-boats; and it is evident, 
from his whole testimony, that the great : 
confidence he places in them is on ac- 
count of their prodigious strength. He 
says, “Their strength is owing to 
their being filled up solid to the floor- 
head; to the timbers being put to- 
gether and diagonally fastened on Sir 
Robert Seppings’s plan; to their being 
caulked inside and out, having no tree- 
nails, but bolted, and copper fastened ; 
the bolts being driven on a ring 
clinched at both ends.” 
Mr. J. Cook, of Glasgow, recom- 
mends that a steam-vessel of one hun- 
dred and eighty tons should be built 
with a seantling for a sailing-vessel of 
twice thattonnage. Mr. Roger Fisher 
says, ‘‘ There has been, in my opinion, 
a great improvement made in the 
strength of steam-vessels built here 
(Liverpool) lately; that is, by carrying 
the frame-timbers up so as to form the 
projection of the sides, and then regu- 
larly planked up solid as any other 
part of the vessel, by which means they 
are much safer.” Mr. Bruncl, when 
asked whetker he would recommend a 
stcam-boat to be built much stronger 
than usual for sailing vessels, gave the 
committee to understand, that great 
weight would be injurious, by lessening 
the buoyancy of the vessel; but Captain 
Rogers's evidence corroborates ' the 
opinions of the other witnesses, and 
seems to shew that this inconvenience 
does not foilow. 
3, Machinery. ° 
The steam-engine, employed on- 
board ships, is as yet a much less per- 
fect machine than when it is used on 
land; the height of the cylinder is 
nearly one half less; the power is 
thereby cramped by short strokes, 
which are inealeulably bad. In this 
way there is a great loss of power, as 
the vis inertia is to be overcome on 
every stroke; more frequent alterna- 
tions are necessary of the beam, the 
piston, and the valves, which oceasion 
yoore wear and more friction than 
Select Committee of the (Touse of Commons. 
341 
where the cylinders are made longer. 
There is also a considerable loss of 
power in converting the alternate mo- 
tion of the piston into the rotary mo- 
tion of the paddles. 
The great size of the boilers, as now 
made, is very disadvantageous, They 
occupy a very inconvenient portion of 
the space within a vessel. 
Vhe method of fixing the paddles is 
avery defective part of the machinery: 
the oblique action of them in entering 
and departing from the water, pro- 
duces that tremulous jarring which 
serves to loosen the seams and the 
bolting of the knees and beams of the 
vessel; it also occasions a very great 
loss of the steaming power. 
In respect to the degree of strength 
proper to be given to the machinery, 
almost all the engineers, who haye 
been examined, concur in the opinion 
that it ought to be very considerable. 
Messrs. Wood say, “all the connecting 
machinery should be twice the strength 
for ordinary work on-shore. Mr. 
Donkin says, that every part of the 
engine should be made at least of three 
times the strength, which, by estima- 
tion, would be required for any force 
to which it might be exposed. “ Ac- 
cidents,”’ he observes, “are most 
likely to happen at a time when the 
suspension of the power of the engine 
would be most fatal.” 
Wrought-iron is strongly recom- 
mended to be used in place of cast- 
iron; and, though some of the witnesses 
have expressed doubts of the practica- 
bility ofmaking largeshafts of wrought- 
iron, Mr. Donkin does not hesitate to 
say, that “they can always be got 
quite perfect, if a sufficient price is 
given for them.” 
As so much of the safety of the ves- 
sel depends upon the workmanship of 
the materials, they should be proved 
before they are used, by a’ proper 
proving engine for trying their strength, 
as well by a force acting in a twisting 
direction, as by a Strain in the direc- 
tion of their length. 
‘It may be collected from the evi- 
dence, that the ereater part of the 
breakages which have occurred. of 
different parts of the machinery in 
steam-boats, has been owing to. the 
negligence of the engine-keepers, 
Starting the engine without clearing 
off the water which is formed on the 
top of the piston, from condensed 
steam, is one cause of fractures ; other 
accidents have arisen-from suffering 
the 
