RARE & UNUSUAL 1910 PATENTED 'GOTEM' RAFTER SQUARE

Stamped 'MANF'D BY ROSS & CLEMENTS VANCOUVER B.C' and 'R & A GOTEM SQUARE PAT SEP 27 1910'. 

Very unusual aluminum patented square with two steel rules. Clearly a rafter framing square as there are designations for 'Hip and Valley' and 'Rise Per Foot'. Appears complete but I can't find any information on it. Good overall condition. Made in Canada.