heinrich daniel ruhmkorff was a german instrument maker who commercialized the induction coil, often referred to as the ruhmkorff coil. born on january 15, 1803, in hanover, germany, he changed his name from 'rühmkorff' to 'ruhmkorff' when living abroad. after an apprenticeship with a german mechanic, he moved to england and later set up a shop in paris in 1855, gaining a reputation for the high quality of his electrical apparatus. although often credited with inventing the induction coil, it was actually invented by nicholas callan in 1836. ruhmkorff improved the design and patented his vers…