Tinnitus, Telephone.
A nervous affection of the ear, of the order of professional cramp; it
is attributed to too much use of the telephone.
Tin Sounders.
A recent addition to the single needle telegraph. (See Telegraph, Single
Needle.) It consists of small tin plates, cut and bent, and so fitted in
pairs to the instrument, that the needle as deflected strikes one or the
other on its right and left hand movements. The sounders can be made to
give sufficiently distinctive sounds to make sound-reading, q. v.,
possible. Commercial tin plate, which is really tinned iron, seems to
give the best results.
Fig. 337. TIN SOUNDERS.
Tissandier's Solution.
A solution for bichromate batteries. It is composed as follows:
Water, 100 parts by weight
potassium bichromate, 16 parts
66° sulphuric acid, 37 parts.
Tongue of Polarized Relay.
The German silver extension of the vibrating or oscillating member of a
polarized relay, corresponding to the armature of an ordinary relay.
Tongue of Polarized Relay, Bias of.
In a Siemens' polarized relay the pole pieces are adjustable so that
they may be brought nearer to or withdrawn from the tongue. One of the
poles is adjusted so as to be nearer the tongue. This one-sided
adjustment is the bias. Its effect is that when the relay is unexcited
this pole attracts the armature so that it normally is drawn towards it.
This ensures the normal contact of the tongue either with the contact
point, or with the insulated stop piece or adjustment screw. Without
bias the armature remains in contact with or drawn towards whichever
pole it was last attracted to. In its usual use a bias is given it.
Top, Magnetic.
A toy illustrating magnetic attraction. It consists of a disc or body of
lead or other material, through which a magnetized steel spindle pointed
at its lower end is thrust. A number of short pieces of iron wire are
used with it. It is spun like an ordinary top upon the point of the
spindle and one of the pieces of iron wire is laid by the side of its
point. As it turns the magnetic adherence causes the piece of wire to be
carried along in one direction by the rotation of the spindle, until the
end is reached, when it goes over to the other side of the spindle and
travels back again.
By using bent pieces of wire of various shapes the most curious effects
are produced. Circles and S shaped pieces give good effects. To increase
the mysterious effect covered iron wire (bonnet wire) may be employed.
Fig. 338. MAGNETIC TOP.