Lawrence Engineering Services Molecular Ratio Slide Rule (for Portland Cement calculations?)

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Country of manufacture: USA,            Date of manufacture: ____
Overall length: 26.7 cm,          Width: 28.8 cm,           Weight: 29.9 gms
Materials: plastic printed scales laminated onto wood, closed form simplex type
Cursor: 2.0 X 3.2 X 0.8 cms; all plastic; lines = one on front only
Scales: 6
Front: D₁ [ SiO₂, Al₂O₃, Fe₂O₃, CaO, M.R. ] D₂
Back: Instructions for use
Back of Slide: Blank
Gauge Marks: [      ]
Condition: C2 (Mint but no paperwork or manual)

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