the importance of this mode of storing energy had become of practical
importance, and great credit was due to Faure, to Sellon, and to
Volckmar for putting this valuable addition to practical science into
available forms. A question of great interest in connection with the
secondary battery had reference to its permanence. A fear had been
expressed by many that local action would soon destroy the fabric of
which it was composed, and that the active surfaces would become coated
with sulphate of lead, preventing further action. It had, however,
lately been proved in a paper read by Dr. Frankland before the Royal
Society, corroborated by simultaneous investigations by Dr. Gladstone
and Mr. Tribe, that the action of the secondary battery depended
essentially upon the alternative composition and decomposition of
sulphate of lead, which was therefore not an enemy, but the best friend
to its continued action.

In conclusion, the lecturer referred to electric nomenclature, and to
the means for measuring and recording the passage of electric energy.
When he addressed the British Association at Southampton, he had
ventured to suggest two electrical units additional to those established
at the Electrical Congress in 1881, viz.: the watt and the joule,
in order to complete the chain of units connecting electrical with
mechanical energy and with the unit quantity of heat. He was glad to
find that this suggestion had met with a favorable reception, especially
that of the watt, which was convenient for expressing in an intelligible
manner the effective power of a dynamo machine, and for giving a precise
idea of the number of lights or effective power to be realized by its
current, as well as of the engine power necessary to drive it; 746 watts
represented 1 horse-power.

Finally, the watt meter, an instrument recently developed by his firm,