HEAVY-OIL ENGINES FOR MARINE PROPULSION. 253 
The reason for this record being made was that there seemed to be some differ- 
ences in studying electrical propulsion, as to the need of torque in reversing vessels, 
and the conditions in this electrically propelled vessel being easy of comprehension, 
and as the investigation would be of much practical value, I thought it worth while 
to have some apparatus arranged by which the differences could be studied. 
This paper was prepared and the data was got together a comparatively short 
time before these papers had to be published, and the work of transcribing the 
records and making up curves from them took a good deal longer than was antici- 
pated, and the paper had to be printed, and I had to send it off without giving very - 
careful study to the records themselves, and while these curves show exactly the 
conditions observed, it is probable that there are some discrepancies which are not 
explained in the paper. Mr. Babcock discovered one or two of these discrepancies 
yesterday, and I talked on the telephone to Schenectady, and I expect to get a 
partial explanation of what he has called attention to, but I think that these dis- 
crepancies have no particular bearing on the purpose of the paper, which is to show 
the propeller action. 
Mr. Babcock has called attention to the fact that on the sheet of general per- 
formances the vessel is shown running to a maximum of 10.5 miles, and that in one 
of the sheets of performance the speed in feet figures up to 11.8 miles. 
This discrepancy arises from the fact that an error was made in plotting the 
first point on the speed curve in question and the speed of the boat on this curve at 
time of reversal should have been a little over 900 feet a minute instead of 1,100 as 
marked. 
It is probable that there is some error in many of these speeds since the boat was 
run near the mouth of the Chicago river and the depth of the water varied con- 
siderably in different parts of different runs. Shallow water may have easily 
affected some of the results. 
