1874.] Economy of Fuel. 69 
away without doing any effective work. Although, in both 
these cases, the greater portion of the fuel remains behind 
until it is wholly consumed, only a small proportion of its 
effective value is retained, whilst the greater part is lost, 
representing so much waste of fuel, a great portion of which 
must be looked upon as avoidable loss. 
To turn now from generalities to the practical working of 
the question, we shall proceed to consider first the appli- 
cation of these principles in the manufacture of iron, which 
branch of industry alone consumes about one-third of the 
total amount of coal raised in the United Kingdom, and 
which, therefore, most largely affects the great coal question 
of the present day. 
Taking the results of iron manufacture in Scotland, we 
find, upon the authority of Dr. Percy, that the ton of pig- 
iron, as made in 1829 at the Clyde Iron Works, required the 
coke of 8 tons 17 cwts. of coal ; whilst in the following year, 
owing to Neilson’s invention of the hot-blast to iron furnaces, 
the introduétion of air heated to 300° F. brought down the 
consumption per ton of pig to 5 tons 34+ cwts. 8 cwts. of 
coal were consumed in heating the blast, so that the actual 
saving per ton of pig-iron was 23 tons. In 1833, when raw 
coal had come to be used instead of coke, 1 ton of pig-iron 
was made with 2 tons 53 cwts. of coal, which, with 8 cwts. 
for heating the blast, made a total of 2 tons 134 cwts. Hence 
by the application of the hot-blast, the same amount of 
fuel reduced three times as much iron, and the same amount 
of blast did twice as much work as previously. 
Subsequently to the attainment of the foregoing results 
an increase in the size of the blast-furnace has been followed 
by still further economy in fuel used in the manufacture of 
iron. The discovery of this fact is due to the iron smelters 
of Cleveland. When the first blast-furnace was ere¢ted in 
that district by Mr. John Vaughan, in 1851, the practice of 
older districts was followed, and the furnace was made 
42 feet high by 15 feet diameter at the bosh. Up to 1858 
there was a gradual increase of size, the furnaces that year 
being 56 feet in height by 16 feet bosh. ‘The results of this 
increase of size were so satisfactory that Mr. Vaughan was 
led to rebuild one of the old furnaces, increasing its size to 
61 feet high by 16 feet 4 inches bosh. This may be said to 
be the first decided step towards the great increase in size 
which followed, the comparative results being so much in 
favour of the large furnace over the original small one that 
it soon became an undoubted fact that economy was to be 
found in that direCtion. Although the scientific reasons 
