6i 



nth April, i< 



John Brown, Esq., in the Chair. 



Professor Fitzgerald read a Paper on 

 THE ACTION OF SCREW PROPELLERS. 



Professor Fitzgerald dealt with the ideas that underlie the 

 mechanics of the subject. The first fundamental idea in the 

 matter is that if the propeller pushes the ship forward it 

 must push the water backwards. That idea, he pointed out, 

 has been sometimes forgotten, and was first brought out 

 distinctly by the late Professor Rankin. 



J. H. H. Swiney, Esq., Bac. Eng., T.C.D., also read a Paper on 



THE MECHANICAL REMOVAL OF DEPOSIT FROM 



WATER MAINS, AS CARRIED OUT AT 



OMAGH IN 1887. 



For some time previous to the Autumn of 1886 the town of 

 Omagh had been suffering from a water famine, and the sanitary 

 authority, who attributed this to the increased and increasing 

 number of house services, together with the small size of the 

 main supply pipe, instructed Mr. J. L. D. Meares, C.E., of Newry, 

 and myself, to examine and report as to the cost of laying down 

 a new main. 



