n the manufacture of his alternators.
Each coil, he said, was tested to double the pressure of the completed
dynamo, but when they were all fitted together, their insulation broke
down at the same volts. The difficulty had been overcome by making the
separate coils to stand much higher pressures. Prof. Rucker called
attention to the fact that dielectrics alter in volume under electric
stress, and said that if the material was imperfectly elastic, some
loss would result. The president said that, as some doubt existed as
to what Mr. Ferranti had actually observed, he would illustrate the
arrangements by a diagram. Speaking of condensers, he said he had
recently tried lead plates in water to get large capacities, but so
far had not been successful.

Mr. Swinburne, in replying, said he had not made a perfect condenser
yet, for, although he had some which did not heat much, they made a
great noise. He did not see how the rise of pressure observed by Mr.
Ferranti and Mr. Kapp could be due to resonance. Mr. Kapp's experiment
was not conclusive, for the length of spark is not an accurate measure
of electromotive force. As regards Mr. Mordey's observation, he
thought the action explicable on the theory of the leading condenser
current acting on the field magnets. The same explanation is also
applicable to the Deptford case, for when the dynamo is direct on, the
condenser current is about 10 amperes, and this exerts only a small
influence on the strongly magnetized magnets. When transformers are
used, the field magnets are weak, while the condenser current rises
to 40 amperes. Mr. Blakesley's method of determining losses was, he
said, inapplicable except where the currents were sine functions of
the time; and consequently could not be used to determine loss due to
hysteresis in iron, or in a transparent dielectric.--_Nature._

* * * * *

THE TELEGRAPHIC COMMUNICATION BETWEEN GREAT BRITAIN, EUROPE, AMERICA,
AND THE EAST.

By GEORGE WALTER NIVEN.

There are at present twenty-six submarine cable companies, the
combined capital of which is about forty million pounds sterling.
Their revenue, including subsidies, amounts to 3,204,060L.; and their
reserves and sinking funds to 3,610,000L.; and their dividends are
from one to 143/4 per cent. The receipts from the Atlantic cables alone
amount to about 800,000L. annually.

The number of cables laid down throughout the world is 1,045, of which