Honeywell tells the story of their Aquastat in this document. It is not dated, but is probably from the 1950s.
This document contains the manufacturer's instructions for the HB Smith Series M450L Mills Water-Tube Boiler for automatic firing with oil or gas (Steam, Vapor, or Water ...
This document contains the jacket assembly instructions for the HB Smith Series 45 Mills Boiler (circa 1979).
This document contains the combustion chamber assembly instructions for the HB Smith Series 45 Mills Water-Tube Boiler for automatic firing with oil or gas (Steam, Vapor,...