1874.] Fuel Economy. 199 ° 
successive action of the bars, and deposited on the dead- 
plate or mouth of the furnace. This is an advantage of the 
greatest importance, as the removal of slag from the extreme 
back of furnaces has always been attended with great 
difficulty and the periodical destruction of the fire. A 
thorough and complete combustion is effected by the 
breaking up and removal of the slag, and consequent free 
admission of air between the bars, and a large saving is 
effected in the usual consumption of coal. 
Mr. Gall, of Halifax, shows a Patent Self-Acting Smoke 
Preventer, with the recommendation that it will reduce the 
smoke emitted from the chimney by seven-eighths; andshould 
this result not be attained the purchaser may, within one 
month, return the Preventer to the patentee, and no charge 
whatever will be made. 
Dingley and Son, of Leicester, exhibit Lake’s Coal 
Economiser, which, according to the statement of the 
patentee, will save from 10 to I5 per cent on stationary 
boilers, and from 20 to 25 per cent on multitubular boilers. 
This arrangement consists of a conical, fluted, or corrugated 
valve, applied to the rear end of the tube, and capable of 
being adjusted as required; the openings round the valve 
being the outlet for the draught, and which are proportioned 
to the area over the bridge, cause the fire to be kept in close 
contact with the plates around and throughout the entire 
length of the tube, ensuring more perfect combustion and 
equal distribution of the heat within the boiler. It is applied 
without in any way altering the boiler or interfering with 
present draught. 
The Messrs. Howard, of Bedford, show their celebrated 
Safety Boiler; and among the leading features of this boiler 
are, safety (every boiler is tested to three times its working 
pressure, and the bursting pressure of the tubes is at least 
1500 lbs. per square inch), great simplicity of parts, facility 
of repairs, and durability. In the Howard Safety Boiler 
there are neither seams nor rivets, and no joint is exposed to 
the direct action of the fire; the tubes are counterparts of 
each other, and every part is made on the interchangeable 
principle ; and it is more readily accessible, both internally 
and externally, for thorough inspe¢tion and cleaning than 
almost any other form of boiler—high pressure steam with 
economy of fuel. With this boiler a pressure of I20 to 
140 lbs. per square inch is more secure than ordinary boilers 
working at 50 lbs., while experience has shown that on the 
great question of the economy of fuel the hopes entertained 
that the higher pressure of steam would, under proper 
