IGO EIGHTH REPORT — 1838. 



On an Improved Method of working the Valves of a Locomotive En- 

 gine. By Mr. Hawthorn. 



Professor Willis described the method recently introduced by Mr. 

 Hawthorn, for working the valves of a locomotive without the usual 

 eccentrics. The motion is derived at once from the connecting rod, 

 by means of a pin placed at the centre of the connecting rod, and giv- 

 ing to a frame a reciprocating motion in a vertical direction at every 

 revolution of the crank. To this frame are attached arms, by which 

 motion is communicated to the slides. It is necessary that the slide 

 should be open for the admission of the steam into the cylinder, a 

 little before the piston has completed the stroke ; this, which is techni- 

 cally termed the lead of the slide, must be provided for with great care, 

 so as to correspond with the various speeds of the piston ; this arrange- 

 ment cannot be made where eccentrics are used without considerable 

 difficulty ; but this is provided for in Mr. Hawthorn's method by sim- 

 ply changing the angle at which the frame is set, an operation which 

 can be performed by adjusting a screw. 



On the Application of Machinery to the Manufacture of Steam-Engine 

 Boilei-s, and other Vessels of Wrought Iron or Cojyper, subject to 

 Pressure. By Wm. Fairbairn. 



Having described the usual process of hand-riveting, and the im- 

 perfections to which it is subject, the author adverts to the riveting 

 machine, which obviates these defects, and produces sound and perfect 

 work. As the time occupied in the process of hand-riveting, allowing 

 the rivet to cool, and thus destroying its ductility, is the chief cause of 

 all the defects, it is evident that an instrument having a force to com- 

 press the rivet within an indrfinitely short period must obviate or en- 

 tirely remedy these evils. The commencement of the process is the 

 same in both methods. In a circular boiler, such as is represented at 

 A, in the annexed figure, the plates having been first bent to the circular 

 form, with all the requisite holes punched in them, two rings of plates 

 are put together by temporary bolts, and suspended over the machine, 

 by three chains, from blocks over the centre of the boiler. These blocks 

 are arranged to move backwards and forwards for circular boilers, to 

 suit any diameter, and are also made to move crossways for plain flat 

 work. Having now placed the boiler so as to inclose the circular por- 

 tion of the machine marked L, (which performs the part of the " holder- 

 on,") and having brought the rivet-holes in a line with the dies marked 

 I and K, a rivet being previously inserted, and the bent lever c, turning 

 on the centre r, being lifted up by the power used to work the machine, 

 — the die i is advanced through the fixed head p, and the rivet is now 

 compressed with great force against the die k. The faces of the dies 

 have each a circular cavity, when employed in the performance of the 

 usual work, but may be formed so as to give any required shape to the 

 head and point of the rivets. 



