1822.} 
heavy scas; and in cascof injury to one 
engine, the other is available.” 
It appears from Mr. Brown’s evi- 
dence, that two fifty-norse engines will 
weigh from twenty to twenty-five tons 
more than two forty-herse engines; the 
weight of the latter, with coal and wa- 
ter complete, being one hundred tons, 
The additional expense would be about 
1,000]. the expense of two forty-horse 
engines being about 6,000!.  Accord- 
ing, therefore, to the opinions already 
stated, when a vessel will contain two 
fifty-horse engines, it will be decidedly 
better to have them of this power than 
two of forty-horse power. 
It appears frem the evidence, that 
attempts are now making, by very in- 
genious individuals, to remove some of 
those defects which have been described 
to belong to the engines now in use. 
~ -Mr. Brunel is engaged on a plan for 
making the engine more compact and 
more simple, and at the same time 
stronger; and to enable it, by certain 
mechanical combinations, to adapt and 
accommodate itself to all the exigen- 
cies, and to all the perturbations inci- 
dent to its peculiar services. 
Mr. Galloway and Mr. Perkins feel 
confident, that high-pressure boilers 
may be so contrived as to be used with 
the greatestadvantage. Mr. Perkins, 
in his answers to the circular queries, 
gives such strong evidence in favour 
of them, from the actual use of them in 
150 American steam-boats, as to go far 
towards removing the prevailing ob- 
jections to them. 
Mr. Donkin is of opinion, that a 
rotary furnace, on Mr. Brunton’s prin- 
ciple, may be applied to steam-vessels. 
Mr. Oldham, of the Bank of Eng- 
land, has invented a plan of revolving 
paddles, to avoid the defects of the 
fixed paddies, as now used. He states, 
that the violent action of the paddles 
of common wheels, in striking the wa- 
ter in a rough sea, is entirely removed 
by the use of the revolving paddles, as 
they enter and rise out of the water 
with a peculiarly soft and easy motion. 
The precise merits of this invention 
will soon be ascertained, as these new 
paddles arenow fitted to the Waterloo 
packet, which plies regalarly between 
Dublin and Liverpool, and tothe Aaron 
Manby, iron steam-boat, lately sent 
from England to Havre-le-Grace, to 
be used on the Scine. 
’ Mr. John Gladstone, 
Douglas, has invented another plan of 
paddies, He employs a pair of 
F 4 
Select Committee of the House of Commons. 
of Castle” 
343 
wheels at each side of the vessel, hav- 
ing two endless chains acting on them, 
with paddles fixed on these chains ; 
and, so far as the plan has been tried, 
ona very small scale, it has been suc- 
cessful. Several attempts have been 
made to get rid of the use of external 
wheels, but hitherto without success. 
Mr. Field has invented a flexible 
metallic ‘piston, which has proved of. 
great utility. 
The merit of first applying steam-en- 
gines to sea-navigation is certainly due 
to the skill and enterprise of the engi- 
neers and shipbuilders of the Clyde ; 
for it was, unquestionably, the success 
of their steam-boats on the Holyhead 
station which led the Post-office to es- 
tablish their boats for keeping up the 
communication between the two coun- 
tries. At the same time it is but jus- 
tice to say, that the public are greatly 
indebted to the Post-office for having 
exercised «ich a sound judgment, in” 
directing their vessels to be built of 
that great strength, which has been so 
often mentioned in this Report; and 
which, at the same time thatithas been | 
the cause of their complete success, 
has also established anew principle of » 
certainty and security in the system of 
steam-nayigation. 
4, Sails. 
Captain Rogers says, “they assist a 
vessel very much; that they can be 
used at all times, except within four 
points of the wind, aiid that they serve 
to keep the vessel steady.” He recoin- , 
mends a large lug-sail forward, a jib, 
and fore aud aft main-sail; to have a 
square top-sail on-board, and a gaft top- 
sail aft; with means of sctting a top- 
mast, but not to use it unless the en- 
gine was out of order. Several plans 
have been tried for getting the wheels 
out of geer, and for moving the paddle- 
boards from the extremity of the , 
wheels towards the centre, and some of 
them successfully. By these means a 
vessel, in case the engine cannot be 
used, may be sufficiently well managed 
with the sails, as to carry her safely into 
port. The evidence of all the other 
witnesses goes to show, that any at-. 
tempt to carry canvass beyond a cer- 
tain moderate quantity will be at- 
tended with a greatimpediment to the 
steaming power, 
—— 
SOCIETY OF ARTS. 
Method of Ventilating Coal Mines, by 
Mr. James RYAN, 
The presen mode of yentilation 
CoMviste 
