A NEW PROPELLER.--The Detroit Tribune says that E. B. Ward has a new boat in the process of construction at Newport, which will be propelled on a principle unlike anything ever seen in western waters, but which has been tested a New York with very satisfactory results, particularly in regard to speed. She will be what is called a beam-board propeller, with an engine working athwart ships, every stroke of which will produce two and a half revolutions of the wheel. The new boat will have 187 feet keel and 24 feet beam. The engine is being built at the Detroit Locomotive Works and the Messrs. Brennan are making the boilers at Newport. She will be ready for business in the Spring.