An elementary book on electricity and magnetism and their applications . Fig. 324. — Flame arcmade with impregnatedcarbons beneath a vit-reous canopy. 462 ELECTRICITY AND MAGNETISM To-. Magnetite, etc. Fig. 325. — Luminous arc lamp with copper electrodeand diagram of connections. Unlike other arc lamps, this luminous arc lamp (Fig. 325), as itis sometimes called, is not adapted to interior use on constant-voltage circuits, Starting Resistance V^i but is USed for street lighting onconstant-currentcircuits. Since thismagnetite arc is ad-c. lamp, it isusually suppliedfrom a-c. lines bymercury-arc
An elementary book on electricity and magnetism and their applications . Fig. 324. — Flame arcmade with impregnatedcarbons beneath a vit-reous canopy. 462 ELECTRICITY AND MAGNETISM To-. Magnetite, etc. Fig. 325. — Luminous arc lamp with copper electrodeand diagram of connections. Unlike other arc lamps, this luminous arc lamp (Fig. 325), as itis sometimes called, is not adapted to interior use on constant-voltage circuits, Starting Resistance V^i but is USed for street lighting onconstant-currentcircuits. Since thismagnetite arc is ad-c. lamp, it isusually suppliedfrom a-c. lines bymercury-arc recti-fiers (described insection 292), orin some cases byBrush arc Mercury-vapor lamps. The commonest form of mer-cury-vapor lamp, known as the Cooper Hewitt lamp, consistsof a glass tube about 1 inch indiameter and 2 or 4 feet long,with mercury at the lower endand an iron or graphite elec-trode at the upper end. The tubeis exhausted so that the pres-sure is only 1 or 2 mm. Thecurrent will not flow throughthe tube from B to A (Fig. 32(3)unless there1 is a stream of mer-cury vapor in carry it. The simplest way to start thelamp is to tilt the tube until athin str
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmagnetism, bookyear19
