284 Proceedings of the British Association. 



Mr. J. Taylor made a few remarks, and observed that the effect of 

 friction on the action of slides, seemed to be in general much over- 

 rated. — Mr. Fairbairn observed, that the invention, if carried into 

 successful operation, seemed adapted to work an improvement in 

 marine engines especially, where room was a matter of great import 

 tance, by lowering the position of the machinery, which appeared a 

 great desideratum at the present day. He objected, however, to the 

 difficulty of obtaining easy access to some parts of the machinery ; the 

 raising of the piston cover, for example, on this construction, would 

 be a laborious operation. After some further remarks, — 



Dr. Greene followed, with a description of Mr. Nasmyth's Steam 

 Hammer for Pile Driving. This machine has been described at 

 former meetings of the Association. Dr. Greene now read a letter 

 received from Mr. Nasmyth, dated Devonport, in which it was stated 

 that at the first trial with a part of the machine at the manufactory 

 it drove a pile 14 inches square, and 18 feet in length, 15 feet into 

 the ground with 20 blows of the monkey, the machine then working 

 70 strokes a minute; the ground was a coarse ground imbedded 

 in a strong tenacious clay, performing this work in 17 seconds. The 

 entire machine is now in full action at Devonport for the embankment 

 to be erected there to keep out the sea, and form a wet dock. He 

 describes it as going far beyond what he had dared even to hope for, 

 and that it is truly laughable to see it stick vast 66-feet piles into the 

 ground as a lady would stick pins into her pincushion. The entire of 

 the operations required to be performed on each pile from the 

 time it is floated alongside of the stage until it is embedded in 

 the solid foundation of slate rock is only A\ minutes. The great 

 stage which carries the machine, boiler, workmen, and every thing 

 necessary, trots along on its railway like a wheel-barrow and moves on, 

 the diameter of a pile, the moment it has finished the last. It pieks 

 the pile up out of the water, hoists it high in the air, drops it into its 

 exact place, then covers it with the great magic cap, which follows it 

 as it sinks into the ground, then thump goes the monkey on its 

 head, jumping away 70 jumps a minute. At the first stroke the pile 

 sank 6 feet, its advance gradually diminishing until in the hard 



