TRANSACTIONS OF SECTION G. 763 



4. A Steady Platform for Guns, t&c, at Sea. By Beauchamp Towee. 



I propose to describe two important improvements which I have introduced 

 into my apparatus for securing a Steady Platform for Guns, &c., at Sea, on which 

 I read a paper at the meeting of the British Association at Newcastle two years 

 ago. It will be remembered that the apparatus consists of a water-dxiven 

 gyroscope revolving in a horizontal plane on a spherical bearing, and directing the 

 action of four cylinders by means of an axial jet, so as to keep the gymbal-hung 

 platform coaxial with the gyroscope. The gyroscope itself was caused to revolve 

 in a horizontal plane by having its centre of gravity about •? inch below its centre 

 of suspension ; this caused it to act as a long-period conical pendulum. If it 

 started with its axis out of the vertical, it would go through a gradually- 

 diminishing conical movement, which would be extinguished by the friction of 

 the bearing. This acted very well in short waves ; but November before last 

 I took my yacht into a long sea in the Channel after a westerly gale, and found 

 that the time during which the horizontal force of each long wave was acting was 

 sufficient to disturb the gyroscope about a degree. This led me to make the 

 following improvement. I lowered the centre of suspension of the gyroscope to 

 the centre of gravity. I made four little pendulums, each 3 inches long, the 

 weight of each bob being only '6 lb. These four pendulums are suspended from 

 the bodies of the four cylinders, and press slightly little wheels on the ends of 

 bell-crank arms on the rim of the gyroscope. They are arranged so that, should 

 the gyroscope be out of the horizontal plane, these pendulums press on it in such 

 a way as to cause it to become horizontal. In the old arrangement the end of the 

 axial jet approached the zenith by a spiral path ; in this improved arrangement 

 it approaches it in a straight line, and, having reached it, has no oscillatory 

 tendency to go beyond it ; so that the time taken by the gyroscope in assuming 

 the horizontal is much shorter than before. The disturbing effect of the 

 horizontal forces of wave-motion acting on the little pendulums is only about a 

 twelfth of what it was when the whole gyroscope was a pendulum ; so that the 

 longest waves produce no sensible disturbance. The machine steadies up much 

 quicker than before, and the slow wandering of the zero through a degree or two 

 has entirely disappeared. 



The other improvement is the addition of what I call the Correcting Cylinder. 

 It is clear that in the arrangement I described two years ago a certain small, 

 lagging-behind error must exist, owing to the necessary departure of the centre of 

 the ports from the centre of the axial jet, in order that the necessary filling and 

 emptying of the cylinders should be performed. I endeavoured at first to diminish 

 this error as much as possible by enlarging the area of the jet and ports relatively 

 to the area of the cylinders, but found a tendency to a hunting oscillation if this 

 was carried too far. I then constructed the correcting cylinder, which has entirely 

 removed this error. 



In the thickness of the partition between each pair of ports I made two other 

 ports, which were merely narrow slits connected by small pipes, one to one end, 

 and the other to the other end of a doiible-acting cylinder, having a piston held in 

 mid-stroke between two stiff', spiral springs, the piston-rod having the elevating- 

 screw of the gun on the top of it. Supposing the centre of the ports to have 

 departed one degree from the centre of the axial jet, one of these narrow-slit ports 

 will in consequence be more covered by the jet, while the other is less covered, 

 and the consequent difference of pressure, acting on the piston and springs in the 

 correcting cylinder, will cause the level of the gun to be altered one degree, so 

 that its axis is still at right angles to the axis of the gyroscope. 



Thus a correction is applied to the gun to compensate for any error in hori- 

 zontality of the platform, whether caused by the lagging behind of the platform 

 over the jet due to motion, or to a disturbing statical movement applied to the 

 platform. 



5. Description of Lewis and Hunter's System of Coaling Ships. 

 By C. Hunter. 



