Book digitized by Google from the library of Harvard University and uploaded to the Internet Archive by user tpb. At head of title: Navy scientific papers, no. 12 On the comparative efficiency of single and twin-screw propellers in deep-draught ships, by W.H. White.--On the elementary relation between pitch, slip, and propulsive efficiency, by W. Froude.--On the use of steel for marine boilers, and some recent improvements in their construction, by W. Parker.--A few years' experience of the screw propeller: its lessons and results, by A.J. Maginnis The resistance given to screw ships by the action of the screw propeller, and how to remedy it, by R. Griffiths.--The steam trials of H. M. S. Iris, by J. Wright.--The minimum area of blade in a screw propeller necessary to form a complete column, by J. H. Cotterill.--Twin ship propulsion, by G. C. Mackrow.--The steam trials of H. M. S. Iris and the resistance of screw propellers, by M. J. A. Normand.--The peculiarities of behavior of steel plates supplied for the boilers of the imperial Russian yacht "Livadia", by W. Parker The influence of cut-off and length of connecting rod on the working of steam engines, by C. E. Stromeyer.--Notes on screw propulsion, by C. Hall