20. Q. How are the sheets of a fire-box supported?

A. They are supported by staybolts screwed through the inside and
outside sheets with their ends riveted over.

21. Q. In what manner is a crown sheet supported?

A. By crown bars or radial staybolts.

22. Q. What are the bad features about crown bars?

A. They are hard to keep clean and frequently cause crown sheets to
become mud burned.

23. Q. What are the advantages of radial stayed crown sheets?

A. They are easier to keep clean and cheaper to repair.

24. Q. How are the inside and outside sheets of a fire-box secured at
the bottom?

A. They are riveted to a wrought iron ring called a mud-ring.

25. Q. Describe the ash-pan and its use.

A. It is a receptacle secured to the fire-box and usually provided with
dampers to regulate the flow of air to the fire. It collects the ashes
that drop from the fire-box and prevents them from setting fire to
bridges or other property along the track. Engine-men must know that