159) The ratio of heat actually used in producing the steam to the heat liberated in the furnace, is known as

160) In a La-mont boiler, there is a __________ circulation of water and steam.

161) The diameter of internal flue tubes of a Lancashire boiler is about __________ that of its shell.

162) Locomotive boiler produces steam at a very high rate.

163) Which of the following is a fire tube boiler ?