196 ROCHESTER ACADEMY OF SCIENCE. [Jan. I4, 



February i8th : Robert Cartwright gave a very interesting and 

 instructive talk, illustrated with black-board sketches, on the "Evolu- 

 tion of Steam Navigation," which was made effective by numerous 

 illustrations drawn from his personal experience in designing and 

 operating marine engines during a period antedating the introduction of 

 the screw propeller and covering active service in the Navy during the 

 Civil War. 



March 4th : J, Y. McClintock read a paper on " City Bridges." 

 The paper covered the subject in general and referred particularly to 

 bridges proposed by him for Exchange Street and West Avenue over 

 the Erie Canal. The paper was supplemented with forty lantern views 

 showing the tendency of European practice, and also showing 

 definitely the plans proposed for this city, one being a lift bridge 

 resting on submerged pontoons for Exchange Street, and an overhead 

 fixed bridge for West Avenue. The discussion was participated in by 

 Messrs. Rafter, Jordan, Mosscrop, Kuichling and others. 



Mr. Jordan presented a plan for Exchange Street providing for 

 counterweights .below the roadway, and for making the bridge of the 

 least possible weight by using plank flooring and providing bearing 

 posts in the center of the canal attached to the bridge so that when 

 raised they fold up against it, so as to be out of the way of boats. 

 The subject was continued to next meeting. 



March i8th : Mr. McClintock explained in detail his manner of 

 estimating the necessary force for operating his bridge with submerged 

 pontoons. 



Mr. Kuichling brought in a German engineering paper which 

 showed that as early as 1888 the plan of applying submerged floats or 

 pontoons was suggested for a canal lift to take the place of locks. 

 The discussion was continued by Messrs. Kuichling, Mosscrop, 

 Skinner, Fisher and Rafter. 



April ist : Upon reading of the minutes Mr. Kuichling said 

 that they should be amplified so as to show, what was the fact, that 

 he had presented the Cierman periodical, not to show that the idea of 

 pontoons as applied to lift bridges by Mr. McClintock was not original, 

 but rather to endorse the practicability — by showing that it had been 

 urged for application to far more important works, and that he believed 

 the idea to be original with Mr. McClintock as claimed by him, 

 although the record showed that it had been originated previously for 

 other applications, and that Mr. McClintock was entitled to credit for 

 conceiving the plan. 



