FIRING WITH VARIOUS FUELS 35 



or crooked, it will be necessary to lay the pieces as com- 

 pactly as possible, and keep the fire-box full all the time. 

 Straight, heavy sticks of hardwood, on the other hand, 

 must be placed so that the flames can pass freely between 

 them. The rear draft door should be opened wide and the 

 front one opened only enough to admit sufficient air. See 

 that the front end of the grates (next to the tube sheet) is 

 kept well covered. If cold air be allowed to pass through 

 to the tubes at this point, the draft will be destroyed. To 

 get satisfactory results, it is often necessary to cover the 

 front end of the grates, for a space of eight inches, with a 

 "dead-plate." A wood fire requires an occasional leveling, 

 but as with coal it is a good plan not to use the poker more 

 than is absolutely necessary. In leveling do not disturb 

 the hot coals on the grates. In firing with wood it is ad- 

 visable to keep the screen in the smoke-stack down, as there 

 is more danger of throwing sparks with wood than with 

 coal. 



How to Fire with Straw. At one time, the return- 

 flue type of boiler was considered the only successful one 

 for straw, but these are now almost obsolete and modern 

 straw burning engines are all of the direct flue type. The 

 Case straw burners are the same as the coal burners, except 

 that they are fitted with straw grates, dead-plates, a brick 

 arch and a straw chute and the boiler is lagged. ( See Fig. 

 9.) Any Case engine, except the eighteen and thirty 

 horse-power, can be made to burn straw by making these 

 changes. 



