gilson-manualfront - Spheresphere.bc.ca/test/manuals/gilsonmanual1.pdfDESCRIPTION. This circular...
14
gilson-manualfront - Spheresphere.bc.ca/test/manuals/gilsonmanual1.pdfDESCRIPTION. This circular slide rule is constructed to give at least ten years service. The Scales are protected