Secondly, when, to obviate this difficulty, the speaker speaks with his mouth very close to the current - regulator, the moisture of his breath condenses upon the contact points or adjacent parts of the regulator, interfering with its action and spoiling the articulation. The improvements relate chiefly to means for remedying or obviating these defects. Prof. Thompson proposes to employ mirrors, sound - reflectors or reverberators (one form of which is shown in Fig. 108. in transverse section), consisting of glass, metal, wood, or other material, by which the soundwaves are turned aside from their direct path, and are made to converge upon the current - regulator, precisely as rays of light may be turned by a mirror. If actual mirrors of polished metal or silvered glass are employed for this purpose, they have the additional advantage of revealing to the speaker the presence of moisture. But in any case the mirror serves to collect the sound - waves as they come from the speaker's mouth, and to direct them on to the current - regulator while intercepting moisture from the speaker's breath: m is the mouthpiece or tube; c, the current - regulator; r, the reverberator. An adjusting screw and an outlet cock for the water which collects in the mouth - tube are also provided where necessary.
The mouthpieces hitherto used on ordinary transmitters are not intended to serve either as reverberators or as protectors from moisture, and Prof. Thompson finds that mouth - pieces for this purpose must, as shown in Fig. 109, be deep and of conical or paraboloidal form. Another part of the invention consists in employing for the current - regulator such materials as are at once neither hygroscopic, nor liable, by their properties with respect to heat, to condense films of moisture, while at the same time they are good conductors of electricity. Prof. Thompson prefers to use as materials for the current regulator, either spongy platinum, carbide of platinum, boron, cake, carbon, or elastic carbon specially prepared, having first deprived such materials of their hygroscople properties by treatment with petroleum, or other suitable hydro - carbon. In some cases, and especially where the contact surfaces of the cur- rent - regulator are of metal, he finds it convenient to keep their surfaces con - stantly moistened with petroleum or other hydrocarbon by supplying them through a cotton filament in communication with a small lubricator.
The improvements also consist in so arrang ing the parts of the current-regulator that the points of loose contact can be actuated by the sound - waves, whilst they are protected from the moisture of the breath by some portion of the conductors or electrodes projecting between the contact points and the breath of the speaker. An example of such an arrangement in given in Fig. 110, wherein the con - protected from the breath by making one of the electrodes in the form of a cup, against the concave face of which the contact - point on the other electrode is directed. The improvements relate further to the form to serve as the current - regulator. The current - regulator of Reis, consisting of one piece of platinum resting lightly against another, is imperfect, except when,as in some forms of Reis's instrument, one or both the pieces of metal are fixed upon springs or some equivalent elastic support; otherwise, the current is liable to very abrupt interruptions. In Fig. 1ll is shown a current - regulator, wherein the two contact pieces are held upon springs s ;. one of these springs is filed to an adjusting frame b, and the other to an insulating block k, for it is found that when there are many points of contact instead of hut a single pair of such points, there is less liability to such abruptness.
Multiple contacts, therefore, are advantageous. One of the, improved forms of current regulator consists of a framework of prepared carbon or metallic tongues, so connected that the current cannot pass from one to the next except through pieces of good conducting carbon or metal, suspended or resting in loose contact against the tongues. In the instrument shown in Fig. 108, the current - regulater c consists of an inclined grating of carbon strips, against which the voice - waves are reflected by the reverberator r, and upon which rest light balls of carbon or metal suspended from hooka by silken strings. In coms cases, where a highly powerful action is desired, the the air-waves are caused to act first on a vibrating tongue, which then transfers the vibrations indirectly to the current - regulator or contact points c. Such a vibrating tongue is shown at In Fig. 112, where it is attached behind a Banged tube t. the contact - points or current-regulator c being on the same face of the tongue v as that against which the voice waves impinge.
This tongue maybe itself an electrode, and serve as part of the current - regulator, in which case It is formed of metal, carbon, or elastic con ductor,whether anhygroscopic or not.
(4) Gower's Telephone is a combination of a telephone and microphone in the same case, which arrangement affords all the advantages obtained by the employment of a battery for communication, without its accompanying objections, and without destroying the effect of the telephone when it is employed as a transmitter in the case of a battery failing. Fig. 113 is a side elevation of the apparatus partly in section, a portion of the side of the box being removed In order to show the communication between the microphone and the principal circuit. Fig. 114 la a plan, the microphone being removed in order to show clearly the arrangement of all the parts on the interior of the box. Fig. 115 is a plan of the underside of 3 the microphone shown In Fig. 113. This microphone is connected with the principal circuit by means of wires, which are broken on in the figures.