CHAPTER VI, 
ALTERNATING MOTORS FOR RAILWAY WORK. 
A vast amount of money, time, and ingenuity, has been 
spent in attempts to develop motorsfor alternating current 
good enough to replace continuous current motors in all 
their varied uses. These attempts have led to many fail- 
ures, but through them all we have come at the present 
time to a very gratifying measure of success. But rail- 
way service is on the whole the severest work to which 
any motor can be put, for it involves severe strains in 
starting, heavy loads on grades, constant and severe shocks 
and jarring, and exposure, usually, to dust and moisture. 
Beyond this a railway motor must be easily reversible, and 
must be able to work week in and week out without close 
attention or frequent overhauling. 
Until very recently these difficulties have deterred 
engineers from any serious attempts to put into use alter- 
nating motors, but the development of electric railway sys- 
tems into conditions that demand the methods and appar- 
atus of long distance power transmission has forced the 
alternating motor into consideration. We have just seen 
the nature of substation distribution for continuous current 
railway motors, and to tell the truth it leaves much to be 
desired. Thelosses of energy incurred in passing from alter- 
nating to continuous current areat best rather serious, the 
apparatus for the purpose is a very considerable item of 
expense and, what is worse, a substation with rotary con- 
verters requires constant attention, so that the cost of at- 
tendance, to say nothing of repairs and depreciation on sub- 
station equipment, makes transmitted power so expensive 
as to bar it from the general use which it finds when not 
necessarily distributed in the form of continuous current.