[1] The filaments in modern "Mazda" lamps, as made at the Edison Lamp
Works, are strips of metallic tungsten.
[2] The batteries we will now describe are for closed-circuit work
_only_, and they are never used for open-circuit work. But there is
a type of battery made that is available for either open or closed
circuit operation. This is the Edison Primary Battery, which will be
described later on.
[3] Practically, there is always one more negative plate than positive
plates in a _regular_ storage-battery cell. Consequently, a standard
cell always contains an odd number of plates.