The Times (London), December 9, 1891, page 5:

THE  THEATROPHONE  IN  LONDON.
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    A preliminary trial of several theatrophones was made at the Savoy Hotel last evening. The machines used are similar to the latest which have been introduced into many Paris clubs and restaurants, and are, it is needless to say, worked on the "coin-in-the-slot" principle. For tentative purposes connexion had only been established with one theatre--the Savoy--and by holding a receiver to each ear the music of the opera was heard with purity and clearness, with good volume of sound. This is true not merely of the solos, but justice was also done even to the choruses and orchestra. The spoken dialogue, too, is excellently reproduced, and delicate shades of intonation are not lost. The mechanism inside the boxes is ingenious and complex, for it has only reached its present form by dint of successive improvements, designed to meet the tricks of those who endeavour to hear without paying, or to hear more than they pay for. It is now believed, however, that the mechanician has finally defeated the swindler. There are two slots--one for shillings, and the other for sixpences, the rate being sixpence for five minutes' music. Time is marked by a small dial, the total of coin received is automatically recorded, while inadequate coins are contemptuously thrown out through a hole at the side of the box. The present intention is to make arrangements--whether by the formation of a new company or otherwise--for supplying London with theatrophones in the same way as telephones are now provided. Among other developments, it is proposed in Paris to establish connexion with the Chamber of Deputies, and to offer at the end of the day a "spoken newspaper," or summary of the events of the day.