Show filaments A difficulty in making filaments ot of non ductile metals like tungsten has been ingeniously overcome in a new patented process ot of the siemens hal like firm ot of germany the tungsten or ether filament metal Is I 1 in D a thin coating of ductile metal and the vi hole is drawn though a die plato plate until the rc required fineness is reached the coated coaled filament attached to a conducting support is exhausted from the hah and an all electric current is turid on alien when the beat quickly drevs off the ductile metal lu etil leaving tur refractory filament ii anent |