The economics of lamp choice

Lamps are first compared with other electrical apparatus as regards the possibility and the method of economic choice. Choice of type (carbon, metallic vacuum and gas-filled) is first considered, and then choice of rating for a given type, the latter being treated both graphically and algebraically. Simple formulÿ are developed for the most economical rating, first with a fixed lamp and then with a fixed candle-power. These are applied to a number of different cases, and various courses of action are suggested for the manufacturer and the lamp user.