iii. The firing and grating to be conducted so as to

interfere as little as possible with the regularity and degree of heating.

In localities where a supply of suitable coal is not available, other methods of heating, such as the use of oil or gaseous fuel, are necessary.

B. To prevent heat losses as much as possible, it is necessary—

i. To avoid leakages of cold air into the furnace. ii. To prevent radiation of heat through walls and roof.