Drip Loop.
A looping downward of wires entering a building, so that rain water, as
it runs along the wire, will drip from the lowest part of the loop
instead of following the wire into or against the side of the building.
Driving Horns.
Projections on the periphery of an armature of a dynamo for holding the
winding in place and preventing its displacement. Various arrangements
have been adopted. They are sometimes wedges or pins and are sometimes
driven into spaces left in the drum core. The toothed disc armature
cores make up an armature in which the ridges formed by the teeth form
practically driving horns.
Dronier's Salt.
A substance for solution for use in bichromate batteries. It is a
mixture of one-third potassium bichromate and two-thirds potassium
bisulphate. It is dissolved in water to make the exciting fluid.
Drop, Automatic.
A switch or circuit breaker, operating to close a circuit by dropping
under the influence of gravity. It is held up by a latch, the circuit
remaining open, until the latch is released by a current passing through
an electro-magnet. This attracting an armature lets the drop fall. As it
falls it closes a local or second circuit, and thus may keep a bell
ringing until it is replaced by hand. It is used in burglar alarms, its
function being to keep a bell ringing even though the windows or door by
which entrance was made is reclosed.