yield, much greater than that of any other system in proportion to its
surface; its small weight in comparison with its yield; and its capacity,
which for an equal weight is greater than that of any other accumulator. In
his experiments in September, 1885, Dr. D'Arsonval obtained with an
accumulator of 2 square meters of surface:

Useful capacity 40 ampere hours.
Total 62 " "
Surface 2 square meters
Charge 10 amp. per sq. meter.
Discharge 20 " " "
Useful weight of lead 10 kilos.

Representing a total capacity of six ampere hours per kilo., and of a
discharge of 5 amperes per kilo., or a total capacity of 81 ampere hours
per square meter, and a useful capacity of 20 ampere hours per square
meter. Subsequently the modification of the negative plate has greatly
improved these figures, which will certainly become much more advantageous
in future. The total capacity of an accumulator having exactly 1¾ meters of
surface has become 87 ampere hours, which if referred to an accumulator of
2 square meters of surface, would give the following results:

Useful weight of lead per sq. meter 5½ kilos.
Total capacity of useful lead per kilo 9.1 amp. hr.
Total capacity per sq. meter 50 "
Useful capacity of per kilo of useful lead 6.23 "
Useful capacity per square meter 34.30 "
Current of charge per square meter 10 amp.
Current of charge per kilo, of useful lead 2 "
Current of discharge per sq. meter 20 "