FARADISM.
The faradic current is chiefly mechanical in. its effects, although, in general, it possesses similar properties to those of the galvanic current in a less degree It is an interrupted, to and fro current, instead of being constant, continuous. Its chemical action is very weak, if it exist at all. and its main utility is for causing contraction and thence stimulating. The action of the battery depends on the principle that " if the conjunc tive wire of the battery (galvanic), coiled on itself and properly insulated, is laid on au insulated surface, and in its immediate neighborhood is placed another coil of insulated wire, connected with a galvauo-multiplier, it is found that when a current is passed through the former the needle of the multiplier is on the instant deflected, then it oscillates a little, and presently comes to rest. If now the circuit is opened the needle is again deflected, but this time in the opposite direction. Instantaneous currents are, therefore, induced in one wire by a galvanic current passing in another wire near it. The wire connected with the battery transmits an inducing current; the secondary wire transmits an induced current." ' Now by rolling these wires into coils these currents are rendered more powerful, and the current derived from the induction coil is intensified by placing pieces of soft iron in the centre of the coil, which, becoming magnetized, as the current traverses the coil, induce instantaneous currents in the coil at the moment of acquiring and of losing its own magnetism. (Bartholow.) The faradic battery then is composed essen tially of the galvanic cell, of two or more coils, and of an apparatus for interrupting the current which is called a rheotome. The current is formed at the time of breaking and of contact, and aside from the con struction and the number of the coils, its effect is dependent on the rapidity of the interruptions. The difference between the poles is not so marked as in case of the galvanic current; the positive pole, however, is more sedative. and the negative more stimulating.
The coils of the faradic battery are different in construction, and the therapeutic effects obtainable from one coil are not similar to those of the other. One coil, the primary, is composed of short thick wire, and the other, the secondary, of long thin wire. The coil of thick wire gives a quantity current, and is especially useful for exciting muscular contrac tions; the coil of thin wire gives a tension current and has a marked sedative effect. These differences in the utility of the faradic current have been in particular emphasized by Apostoli in connection with the electro-therapeutics of the female genital organs.
The gynecologist should either possess a separate portable faradic machine, or else a combination galvano-faradic battery. There are so many excellent faradic apparatuses obtainable now-a-days that the diffi culty will not lie in obtaining a good one but rather in selecting one from others equally good. One of the cleanest and most readily managed is the Kidder tip cup. The Gaiffe, or one of its numerous modifications, or the recently devised Stanley battery, will also be found valuable, especially, as will be noted further on, for use in obstetrical practice, the latter and the Gaiffe because, being so compact, they may be carried without difficulty in the ordinary obstetric bag. The Stanley battery has further•the special advantage of being readily handled without the least risk of spilling the contents of the cell.
These faradic machines we will not specially describe, nor enter into details in regard to their management, for the reason, even as with the galvanic battery, that these are points which can alone be properly learned practically. Where electricity is used as a routine measure in gyneco logical practice we believe it preferable to possess one of the combination apparatuses, because, although only exceptionally useful, it may be desir able to utilize both currents at once.