34 ANNUAL OF SCIENTIFIC DISCOVERY. 



both, and yet economize space in the mid-channel. The appearance 

 of the vessel in the water is not altered in the side view, neither is it 

 much changed in the stern view. The consequence of this new 

 arrangement is, that the rudders and propellers are acting with 

 double effect in each case. The rudders are receiving an increased 

 power, because the impact of the water upon them, takes place at an 

 angle which is constrained by the situation of the keels, and which is 

 the most favorable that can be had. The two propellers, also, revolv- 

 ing as they are in water confined in a limited space, are working to 

 considerable advantage. The effect actually produced is, that, when 

 required, a vessel can be turned about in nearly half the space that a 

 single rudder can turn it, and the two propellers will give a proportion- 

 ate increase of speed. 



The advantages gained by the new construction of the vessel are 

 also considerable. There will be more strength, more bearings in the 

 run, more breadth for cabin room. The rolling and pitching will be 

 reduced very considerably. The vessel wih 1 not make lee-way as 

 formerly ; the vibration, or tremulous motion, will be lessened. The 

 safety of the vessel will be very much increased, because the duplex 

 rudder will have the effect of instantaneously changing the direction, 

 should she be running into some unexpected danger ; also, if one rud- 

 der should be damaged, the other can be used to steer with. The 

 propellers also can be used separately when required. 



STATIC PRESSURE ENGINE. 



CONSIDERABLE discussion has taken place in several New York jour- 

 nals, relative to a supposed new motive power, devised or invented by 

 Messrs. Sawyer and Gwynne, of that city, and which is denominated 

 the " Static Pressure Engine." In the scheme set forth, the compres- 

 sion of atmospheric air is proposed to be made effective by the intro- 

 duction of centrifugal force as an auxiliary agent or power, the initial 

 moving force, or atmospheric pressure, and the auxiliary force both 

 acting on non-elastic fluid or water, which is used as the medium of 

 motion. 



The machine consists of a covered cylindrical basin, 26 inches in 

 diameter and two inches deep, to which is attached a vertical tube 

 four inches in diameter, and of any required length. A spiral groove 

 runs the whole length of the tube, and this, together with the basin, 

 is supposed to be filled with quicksilver. The whole is to be rapidly 

 revolved about a vertical axis, when the centrifugal force of the mer- 

 cury in the basin drives the mercury out through a valve on the edge 

 of the basin, and leaves a vacuum behind. The mercury, as it escapes 

 from the basin, falls into a reservoir communicating with the bottom 

 of the spiral groove, through which it is forced by the pressure of the 

 atmosphere with such velocity that the reaction of the sides of the 

 groove causes the tube and the attached basin to revolve with great 

 momentum, evolving new centrifugal force by which the vacuum is 

 perpetuated. Mr. Sawyer supposes that the centrifugal force of the 

 revolving mercury is sufficient to maintain its OAvn revolution unini- 



