ON A MODEL OF THE U. S. AIRCRAFT CARRIER LANGLEY. 97 
was practically negligible. I think some of the engineers to whom I took occasion to 
show the design previously will be quite surprised at this, but it has been verified in so 
any cases that I am sure it is a fact that the drop is practically negligible. The heat 
transmission running as it does, in one of the tests, at about 750 British thermal units 
per degree, the logarithmic mean temperature difference is remarkably good. Further- 
more, in order to show just what could be done in the way of a high vaccuum, we had 
two ejectors; we put one in use, and we found quite an infiltration of air throughout the 
cast-iron casing of both the exhaust pipe and condenser. Then we put the other into 
use and improved the vacuum considerably. We further improved the vacuum by 
applying a coating of bitumastic enamel on the outside of the condenser and exhaust 
pipe to such an extent that, when we got through, the results with the one air ejector, 
with the bitumastic enamel covering, were identical with the results of the two air eject- 
ors, without any covering, showing that we had a tremendous infiltration of air. 
In making a comparison with several of our merchant ships I have used the same 
surface for 4,280 horse-power as I formerly did with 2,700 horse-power, and with the 
same results; these results, however, being the results of the ordinary trial trip and not 
the results of laboratory tests. Therefore I must not be confused as having stated that 
the condenser is 50 or 75 per cent better than any other. 
These results which we obtain on the Tennessee will really give the difference. How- 
ever, I am sure, in the case of the condensers I have designed previously and those which 
have been designed recently on this new principle, that there can be a saving of more 
that 25 per cent in tube surface ordinarily specified for marine condensers. 
Mr. Lovekin then read abstracts from his paper. 
