.ere w-rl riven niriclinu^ otlxM- woi-ker-, iiiiL;lit lie ))rought i 

 Id. Tlu'oo \;irieties of uiodeU were made, namely, witli 



jhat tlie tendency of tlie body to rovolve o 

 intnxry direction to the screw would caus 

 and hwervinjr of the machines, and that 

 ti opposite directions would be necesr^ary : 



ilus is tiiou<,dit to show that as pi-opellers the screw and the 

 trochoided plane are about (Mjually et!W-ti\e, and that if either has 

 the advanta<,a^ competition will brin.y it to the surface ; a feature 

 of these machines is the triliin,-,' amount of thrust that moves a 

 ^f>Tii]),u-atively heavy bo<ly hori/ontally when suy)ported by a large 



