Contrivances Which Pay a Double Debt.
A lamp commonly used by camping parties, and well worthy of wider employment, is at once a source of heat and light; while it boils a kettle it sheds an ample beam upon one’s table or book. Just this union of two services may be found in the crude lamp of the Eskimo.
Many processes of manufacture once separate are now united with economy of time and power. Steam cylinders for mangling, ironing and surfacing paper, effect smoothing and drying at one operation. Green lumber for making furniture is bent and seasoned at the same time. Wire is tempered as drawn. At first reflectors were distinct from lamps; in an excellent form of [incandescent bulb] the upper part of the container is silvered, increasing the efficiency of reflection in decided measure, as shown on page 75.