Very little information is known concerning the now closed Detroit Lamp Works. The only reference to its existence is in the book of Covington, which cites it as having been founded by the Hylo Company. That rather innovative lamp manufacturer developed an incandescent lamp having two carbon filaments, one small and one large, witin the same glass bulb. Equipped with a special cap having an internal changeover switch which was activated by a pair of pull-strings, the light output of the lamp could be changed from Bright to Dim. The company was taken over by the National Lamp Works of the General Electric Company in 1906.
||The Electric Incandescent Lamp 1880-1925, E.J. Covington, NELA Press 1988, p.33.