Page:Electricity (1912) Kapp.djvu/238

on the way. This merely serves to bring the current into the middle of the main where the feeder is tapped into it. We can still go a step further and arrange for feeding points closer together, so as to reduce still further the length of each section of main in which the voltage drop takes place. This drop may thus be made exceedingly small, even at peak-time, but then we must make such arrangements as will result in a constant voltage at all the feeding points. All the mains in the streets of a town are arranged to form a connected network, and at certain points of this network, preferably those close to districts of great demand, the network is tapped by feeders. Obviously these feeders are not of equal length or equal resistance, and they will certainly not carry equal currents at all times of the day. It becomes, therefore, necessary to adjust the voltage impressed on each feeder or group of feeders at the central station independently, and that is done by the use of so-called "boosting dynamos." These are small machines, which may be regulated so as to raise the voltage at the home end of each feeder by just the amount necessary for making up what at any time is lost by ohmic resistance in that feeder.