xX, W. H, WARREN. 
The advantages of concentrating all the power required fora 
large city in a central power station employing large units was 
forcibly impressed upon me during my inspection of the most 
important power stations in America and Europe, as the primary 
object is the production of electrical energy at a minimum cost, 
having regard to interest on capital expended as well as 
maintenance. It should however, be borne in mind that where 
there are several long lines to be operated, the cost of copper in 
the conductors would be prohibitive if direct currents were used 
at a pressure of 500 volts. In such cases, the multiphase system 
of transmission, by means of alternating currents should be 
adopted, by means of which a sub-station may be operated 
economically twenty miles from the main generators in the power 
station. Examples of this will be given presently. 
The transmission of the electric energy from the power station 
to the cars will now be considered. The system which is at present 
almost universally adopted is known as the Overhead Wire oF 
Trolly System, which consists of poles on the sides or centre of 
the streets, the projecting brackets carrying the overhead oF 
trolly wire over the centre of the track. The! cables which 
convey the currents to the trolly wires may be laid’ "underground, 
on the side poles, or on each side of the centre of the central poles. 
These are generally much more unsightly than they need be in 
America, but in Philadelphia and Buffalo, although not orm’ 
mental, they are by no means unsightly. The same may be said of 
Havre, Berlin, Brussels, Ziirich, and in several other cities I visited. 
The trolly wire is usually divided into sections, with a separate 
feeder to each to avoid inconvenience, as in the event of anything 
going wrong in a particular section the rest will be unaffected. 
The return current is conveyed by the rails, which must be suitably 
connected at the joints, or better, by means of an armoured 
copper wire between the rails and connected with them 4% 
intervals, 
The Conduit System was proposed in order to avoid the 
— and obstruction caused by the Trolly system. It is 
