234 DISCUSSION ON 
answered the requirements of the light road remarkably well. 
Tank engines were certainly the most economical for use on rail- 
ways where conditions permitted of their employment. It was 
important to get rid of the tender, which was a mere carrying ~ 
' machine, and so much dead weight; but it often happened that 
water supplies were not sufficiently frequent to suit tank engines. 
The construction engineer said, “I cannot aftord to give you water 
supplies every twenty miles, my estimate only provides them every 
thirty-five or forty miles ;’ therefore the locomotive man had to 
make tender engines for lines which could be worked more 
economically by tank locomotives. | 
He observed the author referred to the use of electricity as a 
possible method of increasing the bite or traction of locomotives, 
but he did not think there was anything likely to arise from that. 
When the Americans first started electrical traction, they were 
surprised at the success of their first attempts, and at the loads 
which they moved up steep inclines. They fancied that the 
electric currents, passing from wheel to rail, increased the tractive - 
power of the motor ; but when they put their machines to test at 
the friction brake, they found them developing such horse powers 
as readily accounted for the results observed. There were one or 
two other matters of sufficient importance to mention. The first 
was superelevation on curves. When passing through America 
two or three years ago, he met Mr. Theodore Ely, who was 
general locomotive superintendent of the Pennsylvania railroad. 
He was at one time resident engineer on that line, and therefore 
fully acquainted with the superelevation given by American 
engineers. He mentioned to Mr. Ely a peculiar action of some 
of the first American consolidation engines (brought to this 
Colony some years ago) when working round the sharp curves of 
the mountain line: the wheel of the bogie on the inner rail of the 
curves was found to lift clear off the rail, when running smartly, 
and spin round in the air. Mr. Ely said their practice was to 
give much greater superelevation than ours—as a rule, one inch 
elevation to the outer rail for every degree of curvature—and 
