Only found 3 x s.f.h in the index, last one probbly about 1913
18,349,20,Queries and Replies,18488. Converting 500-watt Kapp Dynamo to Rotary Converter,,S.F.H.,
18,370,526,Queries and Replies,18349. Small Rotary Transformers; Windings for Automatic Cut-out,,S.F.H.,
29,646,254,Replies in Brief,Casting zinc,,S.F.H.,