4 documents. Two plans showing measurements and details of Duplex Safety Boiler. Plans are drawn on dark blue paper, backed with material. A. On bottom of plan 'Sectional elevations of Duplex Safety Boiler New York 1881' B. On bottom of plan 'Plan for 50 hp Duplex Safety Boiler, ten 5ft sections' C. and D. Accompanying plans are two pages of instructions 'Directions for setting a Duplex Safety Boiler'. Written instructions in white pen on dark blue paper ( difficult to read, some faded ) 12 steps are outlined, with remarks at the bottom of the second sheet. This boiler could have been used in a Lansell mine ? (further research required).bendigo, mining, duplex safety boiler