described in connection with Mix & Genest's board, in addition to a test battery at the exchange. A calling current (fig. 67) passes by a b, K., plug L.S. to earth. When the plug is lifted the phone Kt. is cut in viâ c de k i, J.R., key Tk., test key cт, test battery, and earth. Test is made by applying L.S. to the socket h; line being free, connection is established by pushing L.S. home in the desired jack. The calling battery w.B. is divided into two parts for short and long line ringing. To ring on a short line the key u. is depressed, bringing in contact with g and the cord of the plug L.S. For a long line the key G.B.T. is depressed simultaneously, and the whole battery brought in. After connection is ascertained to be satisfactorily through by the presence on the line of a current from one or both of the subscribers' test cells, the phone is cut out by pushing down U., and so separating the contacts i and k. Key CT is used to cut out the exchange test cell momentarily when currents from the subscribers' cells are being tested for. In addition to the single cords, there are a few double cords with ring-off drops and keys kept in reserve. These are shown at SK/., U., T.', T". Each pair of double cords has a jack m to receive connections from the next table when necessary. n is in connection with the calling battery, and the key K.B.T. is used for ringing through the plug c.s.

The multiple boards in the remaining six Berlin switch-rooms are of Western Electric Company's manufacture. One of them is, for want of room for lateral extension, arranged in two tiers or stories, the operators of the upper tier sitting some six feet above the level of the heads of those below. This is ingenious, and saves space, but is not conducive to health. The lady superintendents, familiar in other countries, are dispensed with; the girl operators, who, as German State officials, are of course in uniform, being kept up to the mark by mature gentlemen of severe and martial aspect. Should the British Post Office take over the telephone exchanges in 1897, a new field for employment would be open to the army reserve men were Parliament to sanction the adoption of the Prussian corporal plan. When located in old buildings, the German switch-rooms sometimes lack cubic content and ventilation; but when opportunity offers,

as at Moabit, Breslau, Frankfort-on-Main, &c., the architecture, decorations, and accommodation are worthy of all praise.

There are seven switch-rooms in Berlin, arranged in an

irregular circle round

the centre of the city. Each has direct junction. lines to every other, there being some 700 wires so employed, without counting those going to the suburban rooms. All these junctions are single and erected overhead. The trunks all come into one switchroom, and are multipled over small tables, divided from each other by partitions, each of which accommodates two trunk lines and is attended to by one operator. These trunk tables are a speciality of Messrs. Mix & Genest, who have supplied nearly 300 to the Imperial Administration for use in different towns. Fig. 68 shows their general appearance. Each section is fitted with answering jacks for the trunk and intermediate board wires, together with forty repeat

FIG. 68

jacks and the necessary indicators; also a metallic circuit on which branch switch-rooms may be put through to the trunks without the intervention of a translator. The local operators notify trunk

calls to the small boards, and the connections are completed through an intermediate section on which all the local lines are multipled. The trunk tables are provided with sand-glasses on the Swiss plan for checking the duration of conversations. The arrangements are very carefully devised, but the speed and economy obtained would be greater, and the chance of error less, if the trunk girls had the local repeats directly at command. One operator to two trunks appears superfluously luxurious. The translators used are of the double-coil type with yoked cores, the resistance of both primary and secondary being 170 ohms.

To those who understand the possibilities of telephonic switching in the direction of rapidity, and are accustomed to think of demand and connection as a matter of three or four seconds only, the methods adopted in Berlin appear strange, even to the verge of incomprehensibility. The seven switch-rooms are numbered from I upwards, and a subscriber is represented in the list by two numbers, firstly that of his switch-room, secondly that of his line, so that in the same town the same series of numerals is repeated seven times and distinguished by an index number, like so many logarithms. Indices, consisting of short words differing widely in pronunciation-such as the names of colours, of jewels, of rivers, anything-would be much more distinctive and less liable to be misunderstood than a constant repetition of numerals. That confusion is apt to arise is obvious from the rule which enjoins the calling subscriber to mention the number and name of the switch room to which the person he wants is connected. Thus, to quote the rule, No. 3 switch-room must be asked for in a ten-syllable formula, Amt drei, Oranienburgerstrasse.' The following indicates the steps of a Berlin connection through one switch-room when the fates are propitious and the course of telephony runs smooth. A wants B.

Operation 1.—A takes one of his two telephones off its hook and applies it to an ear.

If he happens to take

[He is instructed to do this, but is not told which. the left-hand one-and a stranger would be as likely as not to do so- he cannot ring the exchange, and naturally does not get any answer. It is true that in another part of the instructions he is advised to leave both telephones in their places when not corresponding, and in any case to leave the one on the