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 13/4 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 51/2 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 "
Current of discharge per kilo, of useful lead 4.56 "

The next advantage of the Montaud accumulator is the ease with which it can
be taken out of its box and repaired without special tools and experience.
A capital defect in this respect has hitherto much interfered with the use
of accumulators. In case of accidents, several kinds of which are possible,
it is found very difficult to rectify the apparatus. The Montaud
accumulator is much less liable to accidents, on account of the firmness
and compactness of its construction, and if any accident happens, the
repairs are simple and easy. Lastly, the stout framework secures the
apparatus from any accident due to a disproportionate charge or discharge.
The peculiarities of the combs and rods already described solve this
problem. On September 8, 1885, Dr. D'Arsonval, professor at the College of
France, wrote as follows: "The Montaud accumulator is of the Plante type,
and is extremely well conceived from a mechanical point of view. The
wooden combs prevent the plates from coming in mutual contact, and give the
apparatus great solidity. The process of formation is ingenious and rapid.
To give 1 square meter a capacity of 20 ampere hours, there is required
only a quarter of an hour's treatment.

"To obtain the same result by Plante's method, months are required. The
entire experiments have been effected with No. 2, which has a surface of
two square meters. This apparatus, if charged to saturation, gives 62
ampere hours as its total capacity, and, as in the Plante, this capacity
constantly increase