124) The artificial draught is produced by

125) The draught is the __________ of pressures above and below the fire grate.

126) The function of an eccentric is to provide __________ motion to the slide valve.

127) The water tubes in a Babcock and Wilcox boiler are

128) In case of condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is __________ the atmospheric pressure.