238 Hon. C. A. Parsons [Jan. 26, 



In 1884 preliminary experiments were commenced at Gateshead- 

 on-Tyne, with the view of ascertaining by actual trial, the conditions 

 of working equilibrium and steady motion of shafts and bearings at 

 the very high speeds of rotation that appeared to he essential to the 

 construction of an economical steam turbine of moderate size. Trial 

 shafts were run in bearings of different descriptions up to speeds of 

 40,000 revolutions per minute ; these shafts were lh inches in dia- 

 meter and 2 feet long, the bearings being about •§ inch in diameter. 

 No difficulty was experienced in attaining this immense speed, pro- 

 vided that the bearings were designed to have a certain small amount 

 of li give " or elasticity ; and after the trial of many devices to secure 

 these conditions, it was found that elasticity, combined with frictional 

 resistance to transverse motion of the bearing bush, gave the best 

 results, and tended to damp out vibrations in the revolving spindle. 

 This result was achieved by a simple arrangement ; the bearing in 

 which the shaft revolved was a plain gun-metal bush with a collar at 

 one end and a nut at the other; on tbis bush were threaded thin 

 washers, each being alternately larger and smaller than its neighbour, 

 the small series fitting the bush and the larger series fitting the hole 

 in tbe bearing block, these washers occupying the greater part of the 

 length of the bush. Lastly, a wide washer fitted both the bush and 

 block, forming a fulcrum on which the bush rested ; while a spiral 

 spring between the washers and the nut on the bush pressed all the 

 washers tightly against their neighbours. It will be seen now that, 

 should the rotating shaft be slightly out of truth (which it is im- 

 possible to avoid in practice), the effect is to cause a slight lateral 

 displacement of the bearing bush, which is resisted by the mutual 

 sliding friction of each washer against its neighbour. The shaft 

 itself being slightly elastic, tends to centre itself upon the fulcrum 

 washer before mentioned, under the gyrostatic forces brought into 

 play by the rapid revolutions of the shaft and influenced by the 

 frictional resistance of the washers, and so the sbaft tends to assume 

 a steady state of revolution about its principal axis, or the axis of 

 the mass, without wabbling or vibration. This form of bearing was 

 exclusively used for some years in turbine engines aggregating some 

 thousands of horse-power, but it has since been replaced by a simpler 

 form fulfilling the same functions. In this later form the gun-metal 

 bush is surrounded by several concentric tubes fitting easily within 

 each other with a very slight lateral play ; in the interstices between 

 the tubes the oil enters, and its great viscosity when spread into thin 

 films has the result of producing great frictional resistance to a rapid 

 lateral displacement of the bearing bush ; the oil film has also a 

 centring action, and tends under vibration to assume a uniformity of 

 thickness around the axis, thus centring the shaft, and like a cushion 

 damping out vibrations arising from errors of balance. This form of 

 bearing has been found to be very durable and quite satisfactory under 

 all conditions. 



Having tested the bearings up to speeds above those contemplated 



