Mathematical and Physical Science. 327 



the means which Mr M. proposed to employ to obviate the 

 great expense and inconvenience of such occurrences. 



Mr James Nasmyth then explained to the Section his im- 

 provements in forging iron. In forging shafts for the 

 paddle-wheels of steamers, for example, it was of most 

 essential importance that the shaft should be sound from 

 the surface to the centre. The common plan by which the 

 section was alternately elongated in different directions, 

 could not effect this object. It did, in fact, effectually cripple 

 or disintegrate the central parts of the shafts, just as one 

 by heating a rod of wood would separate the central fibres 

 and thereby weaken it. To prevent this elongation Mr 

 Nasmyth forged his shafts in a hollow wedge, thereby giving 

 rise to three forces converging upon the centre, and thus 

 securing a complete consolidation of the metal. 



Mr Nasmyth then explained his method of welding, shew- 

 ing that a weld was in general so much weaker than the 

 other parts, because of the weld being made from the ex- 

 tremities towards the centre, thus enclosing within it all 

 those omdated and disintegrated portions which, in fact, kept 

 the solid forces of the metal from coming in contact. He 

 proposed that one of the surfaces to be welded together 

 should be slightly convex, that the welding should begin at the 

 centre when the surfaces were in contact and proceed out- 

 wards, thus squeezing out those loose portions, and allowing 

 the two surfaces to come in complete contact with one another. 



Several members having expressed their high opinion of 

 these excellent improvements, 



Dr Robinson said that they bore upon them the impress of 

 mechanical genius, addressing themselves as all such things 

 did, at once to the understanding and approbation of all, 

 and each wondering that they were not found out before. 



Friday, August 2. 

 Section A. — Mathematical and Physical Science. 



Mr Follet gave notice of the working of the new Integrat- 

 ing Anemometer. He had now adopted Dr Robinson's plan 



