To the Editor of the New-York Times: In your issue of last Sunday I was much surprised to find a communication signed W, advocating the use of the double-propeller ... since a boat was built ...

Most famous of these is probably the toroidal propeller that made waves a while ago, mostly in the field of flying drones, but commercial toroidal boat props exist too. Test results of the ...

Ericsson was the inventor of the propeller, and told a curious story about his first propeller boat, and a Commission of the British Admiralty. Mr. Raymond obtained his extraordinary information ...