Helios direct current flaming arc lamps ...
A 1910 trade catalogue issued by the Helios Manufacturing Co. to sell direct current flaming arc lamps and replacement parts to electricians, theatre and industrial lighting buyers. Halftone photographs show coiled resistance units, clamp and thumbscrew hardware, and hands lowering a lamp housing, alongside a line-drawn parts plate numbering dozens of rods, chains, globes and brackets against a flat ground; the plate works as a ready-made catalogue grid of small mechanical silhouettes.
