Stephen Roper 
Roper’s Instructions and Suggestions for Engineers and Firemen Who Wish to Procure a License, Certificate, or Permit to Take Charge of Any Class of Steam-Engines or Boilers, Stationary, Locomotive, and Marine [PDF ebook] 

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. An engineer should close the steam and water valves which form a communication between the boiler and the glass gauge every night, as, if the glass tube Should break in his absence, the escaping steam and hot water from the boiler would most certainly injure any property which might be in the immediate vicinity.