135 
One of the groups is used for producing the minor current 
lor exciting the circles of electro-magnets, while the remain- 
ing groups are joined together for a quantity of seven and 
an intensity of four for the production of the major current 
of the machine. The aggregate weight of wire on the 
electro-magnets is 356 lbs., and on the armatures 26 lbs. 
The helices for exciting the electro-magnets are connected 
with a commutator, while those producing the major current 
are placed in connection with two rings, or in place thereof 
with another commutator, according as the alternating or the 
direct current from the machine is required. The strength 
and proportions of the several parts of the machine enable 
it to be driven with advantage from 300 to 1,000 revolutions 
per minute. 
At the medium velocity of 500 revolutions per minute, 
the major current will melt eight feet of iron wire 0 065 of 
an inch in diameter (No. 16 B.W.G.), and will produce two 
electric lights in series, each consuming carbons half an inch 
square at the rate of three inches per hour. 
When driven at a velocity of 1,000 revolutions (equiva- 
lent to 16,000 waves) per minute, the current will fuse 12 
feet of iron wire 0'075 of an inch in diameter, (No. 15 
B.W.G.) 
At this velocity the light from two sets of carbons in 
series is unendurably intense as well as painful to those 
exposed to its immediate influence. Estimated on the 
basis afforded by the performance of the excellent magneto- 
electric light machines of MM. Auguste Berlioz and Van 
Malderen, who have made a careful study of the photo- 
metric intensity of the electric and oil lights ; the power of 
the new machine is equal to that of 1,200 Carcel lamps, 
each burning 40 grammes (T408oz. avoir.) of oil per hour, 
or of 9,600 wax candles. The amount of mechanical energy 
expended in producing this light is about 10 indicated 
horse power. 
