122 JOURNAL AND PROCEEDINGS 



electrol3^tic action had set in. The tar coating appears of 

 little use to protect the iron. Serious damage, no doubt, to 

 the water pipes is silently going on, as, of course, being 

 buried in the ground, they are hidden from observation. 



In the City of Richmond, the amount of damage done to 

 the water pipes was estimated at $17,000 per annum. At St. 

 Louis it was estimated that 122,980 lbs. of iron was being 

 removed from the pipes by electrolysis. In Pittsburg, Mr. 

 Brownell, an electrical engineer, thus reports : — 



" In the City of Pittsburg there are 62.7 miles of parallel 

 lineal streets jointly occupied by the tracks of railway 

 companies and water pipes. Gas leakage from the mains to 

 the earth decreases the electrical earth resistance and 

 increases the electrolytic disintegration of the subsurface 

 metallic structures." 



He says that electrolysis is eating away the iron beams 

 in the cellars of every fire-proof building in Pittsburg. 

 Reports have been made by expert electrical engineers of the 

 condition and direction of the electric currents in the City of 

 Toronto, London, Ottawa and several other cities of the 

 Dominion, and in all cases severe damage was found to have 

 occurred and was, without doubt, still at work insiduously 

 destroying the iron of the pipes. 



The method usually employed to ascertain the position, 

 strength and volume of the electric currents traversing the 

 city in the neighborhood of the trolley lines, is to make what 

 might be termed an electrical survey. A plan of the city is 

 procured on which the street railway and interurban electric 

 railways are laid down. The volt meter and ammeter read- 

 ings are taken throughout the city and are plotted on the 

 map. The city is then divided into two areas, one called the 

 positive, where the current leaves the pipes and returns to 

 the rails or power house, and the other is called the negative, 

 and is where the reverse takes place, the current leaving the 

 rails to the pipe. It is in the positive area, especially near 

 the power house, where damage to pipes is most to be 

 apprehended. A plan of the above nature reveals at a glance 



