20O AN ELECTRICALLY PROPELLED STEAMER. 



denser, however, was not a success, partly because of the low steam pressure and 

 poor design and partly on account of the use of tallow as a lubricant. The tallow, 

 decomposed by the heat of the steam, formed soluble copper salts which rapidly 

 attacked the iron plates and tubes of the boilers. During this same year, 1838, 

 John Bourne patented the counter-current principle and the carrying of the water 

 in the tubes instead of around them. He did not, however, apply this to marine 

 work until much later, and the first modern condenser of which I have record 

 installed in a ship was put in the Alar in August, 1857. About the same time 

 Pirrson's condenser, a combination of surface and jet, came into use to some extent 

 in marine vessels. Mr. J. F. Spencer also had considerable to do with the intro- 

 duction of the surface condenser in marine use, which must have occurred in the 

 years between 1858 and 1862, although I have no direct records of this. 



The Chairman (Admiral Capps) : — I will now have to enforce our rules as to 

 time occupied in discussion of papers. Nothing but the requirements of other 

 papers would cause the Chairman to curtail the discussion at this point. I think, 

 however, the Society will be only too glad to receive additional comment if members 

 feel so inclined. This comment may be written out and sent to the Secretary, and, 

 as is always the case, the author of the paper will have the opportunity of summing 

 up and saying the last word. 



I think the discussion that has developed this morning has admirably brought 

 out one of the principal objects of this Society, which is, the diffusion of knowledge 

 concerning shipbuilding by an interchange of views of members who have had 

 experience; and nothing seems to bring out the best results in an experience meet- 

 ing than to have advanced a few opinions of widely different character. I think 

 the Society is to be congratulated upon the discussion which has taken place this 

 morning, and I know you will permit me to thank Mr. Donnelly on behalf of the 

 Society for his efforts in bringing forth this discussion. 



On account of the limited time at our disposal the next paper on the list, entitled 

 "Notes on Fuel Economy as Influenced by Ship Design," by Mr. E. H. Rigg, will 

 be read at the afternoon session, and the next paper to be presented at this sitting 

 will be that entitled "Active Type of Stabihzing Gyro," by Mr. Elmer A. Sperry, 

 Member of the Society. This paper will be presented now so that advantage can be 

 taken of arrangements made to project certain illustrations on the screen. 



