1874.| Fuel Economy. 195 
(8). Natural and artificial fuels of all kinds. 
(9). Coal-cutting machines. Peat-manufacturing machines. 
(10). Domestic and other fires, stoves, ranges, and apparatus 
of all kinds (using coal, gas, or other fuel) for cooking, 
and for warming rooms and buildings. 
(11). Mechanical or other arrangements for securing the 
delivery of proved weights of fuel to the domestic 
consumer. 
Entering at the south door is seen a wooden model of 
Davey’s Patent Differential Expansive Pumping Engine, 
200-horse power, for the New Hartley coal-pit ; the engine 
is intended to lift 1500 gallons of water per minute 420 feet 
high. This is exhibited by Hathorn, Davis, and Co., of Leeds. 
On the right-hand side of the building the first object 
which engages our attention is Erskine’s Patent Economiser. 
This consists of Io horse-shoe pipes about 4 inches in 
diameter, and all conne¢ted; these are placed in the flue 
communicating with the chimney. The waste heat from 
the boiler fire encircles these pipes, and causes the water 
which flows through them to enter the boiler at a temperature 
of 280° F.; and as these pipes are liable to become covered 
with soot and dust, instead of having a scraper, as in many 
instances is done, a pipe about 2 inches in diameter passes 
through the entire length of the horse-shoes, which is 
perforated with holes about 6 inches apart. The pipes are 
allowed to get hot, and the steam is now blown on to them, 
which, according to the inventor’s statement, effectually 
cleanses them. ‘The advantages which Mr. Erskine claims 
are, that from the peculiar form of his economiser, it causes 
no diminution or obstruction to the draught in the flue. It 
maintains a thorough circulation of the water through all 
the tubes, thus preventing the accumulation of scale; it is 
easy of access to every part, so that if one of the pipes is 
‘injured it can easily be replaced. 
Andrew Bell shows a fine set of spiral economisers; they 
have the exact shape of three condensing worms put 
together. Each worm consists of 70 feet of pipe, and a 
three-coil machine is sufficient for a 4o-horse boiler. Mr. 
Bell has shown great ingenuity in the casting of these iron 
worms; it would not be an easy undertaking to cast the 
worms in one piece—in fact practically impossible. The 
spirals are cast in half circles, having a spigot and facit 
joint. The joints fit so well into each other, that the circle 
can be formed and lifted without the joints parting ; moulding 
boxes are put round these joints, and hot metal run upon 
them, so that it forms a perfect spiral when they are all 
