AND APPLICATION OF THE STEAM-ENGINE. 1 j 



In tracing the progress of the arts of Ship-building and 

 Navigation, in the remarks on the intimate nature of that 

 change in the pursuits and conduct of the human race termed 

 Civilization, with which I commenced, the influence of tin- 

 adoption of the compass in directing vessels at sea, and that of 

 some other improved means of guidance over the waters, 

 successively employed, were purposely neglected ; on account 

 of the length to which my introduction must have been ex- 

 tended, had those points been duly considered. But a portion 

 of the history of these subjects I shall now introduce, in some 

 detail, because, while it affords a remarkable example of the 

 utility of scientific knowledge in advancing the useful arts, it 

 is also at present far less known than it deserves to be. 



I allude to the discoveries in the science of Magnetism, by 

 which Mr. Peter Barlow, of the Royal Military Academy, at 

 Woolwich, has been enabled to counteract the effect on the 

 compass, of what has been termed the Local Attraction of 

 vessels, which, but for the masterly investigation of that na- 

 tural philosopher, would, ere long, have rendered it necessary, 

 either to dispense with the application of iron in the con- 

 struction and equipment of ships, or to have abandoned the 

 use of the compass in navigation, as having become not merely 

 nugatory, but under certain circumstances absolutely mis- 

 chievous. 



" Of the numerous interesting facts with which philosophy 

 has been from time to time enriched," observes a writer in the 

 Edinburgh Philosophical Journal, of whose historical state- 

 ments on the present subject I shall avail myself, " by far the 

 greater number may be traced to some fortuitous or accidental 

 circumstance ; and it belongs perhaps almost exclusively to 

 the nineteenth century, to boast of some valuable discoveries, 



the steam-engine itself, may not be aware of the total extent of our obli- 

 gations to him in connexion with that machine, I have subjoined an extract 

 on the subject from Mr. Davies Gilbert's paper, quoted in a previous note : 



" Greatly as we are indebted to Mr. WATT, [for the improvement in the 

 steam-engine described in the text above,] our obligations to him are still 

 greater for originating and carrying almost to a state of perfection, the ap- 

 plication of steam as a moving power to machinery* in all the complicated 

 and varied uses of mechanical inventions in this country. 



" In effecting this most important object, the double engine was first 

 brought into use, the extremely ingenious contrivance for producing paral- 

 lel motion was invented, and the principle of centrifugal force enabled an 

 apparatus called a Governor to regulate a supply of steam inversely propor- 

 tionate to the velocity which might at any instant be required ; and the use 

 of fly-wheels, perfectly understood in theory, became subservient to the re- 

 gularity of motion, and to the gigantic efforts of our most ponderous ma- 

 chinery. We owe further to Mr. WATT the introduction, at least into ge- 

 neral use, of what is termed bevelled geer" Philosophical Transactions for 

 1830, p. 127- 



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