STEAM BOILERS 353 



glass tube. When these cocks are both open the water 

 will pass from the boiler into the glass and stand at the 

 same level as in the boiler, but if either one of the cocks 

 be closed or the pipes leading to the cocks be stopped, the 

 water would rise in the glass and give a false water level. 

 If it is the upper one that is closed, the pressure in the 

 boiler will cause the glass to fill, and if the lower one is 

 closed, the glass will fill with condensed steam. Below 

 this glass is another cock, which is used to drain the 

 glass or blow out the other cocks. By opening this cock 

 when there is pressure and closing the lower one leading 

 to the glass, the upper one will blow out, or if the upper 

 one is closed and the lower opened it will blow out. It 

 is best to try the cocks every morning and see if they 

 are open or free from stoppage. Always have some 

 extra glasses along, for they are likely to break at any 

 time. 



486. Leveling the water column. Before firing up a 

 boiler a new man should always determine the level of 

 his water in the boiler as compared to the water column. 

 If it is a stationary boiler, take off the manhole cover 

 and fill until the water has reached the lowest limit in 

 the glass. Then continue to fill until the proper height 

 of water has been reached and again note the level in the 

 glass. A good way to mark these points is to file notches 

 in the guard wires which protect the glass. 



Should the boiler be traction or portable, it should be 

 set on level ground and leveled up with a level. Then 

 the water column should be leveled the same as in a 

 stationary boiler. 



487. Feed pipe. There is difference of opinion in re- 

 gard to the place where the feed pipe should enter the 

 boiler. In horizontal tubular boilers it generally enters 

 near the front end and passes back through the boiler to 



