RECENT PROGRESS IN PRACTICAL AND EXPERI¬ 
MENTAL ELECTRICITY. 
BY 
Reginald Fessenden. 
[Read before the Society October 12, 1901.] 
GENERATION OF ELECTRICITY. 
Improvements in the efficiency of generators have been 
for some years a matter of little moment to the electrical de¬ 
signer. The electrical generator is the most efficient mech¬ 
anism in the world. The loss of energy in it is only 2 or 3 
per cent, and if there were any especial object in doing away 
with this slight loss it could easily be reduced to a fraction 
of 1 per cent. Inventors during the past year have, there¬ 
fore, concerned themselves with perfection of mechanical 
detail and in cheapening and standardizing construction. 
The ever increasing use of large generators has presented 
some pretty mechanical problems in the building up and 
ventilation of the armatures and commutators, which have 
been dealt with in a very thorough manner. 
The importance of wave form is now generally recognized, 
and practically all new stations use generators giving a pure 
sine wave. 
In electrical construction three difficulties have become 
more prominent: 
First. Owing to the large units employed, short circuits or 
rushes of current due to dissynchronizing have become very 
serious, as, unless guarded against, sudden localizations of 
energy, measured in tens of thousands of horse-power, may 
easily occur. This has been met by designing the generators 
24—Bull. Phil. Soc., Wash., Vol. 14. 
(167) 
