INTERCONNECTION OF ITS BRANCHES. 187 



be subjectively so they cannot have independence as pre 

 sented to our consciousness ; and this is the only kind of 

 independence with which we are concerned. And here, 

 before leaving these illustrations, and especially this last 

 one, let us not omit to notice how clearly they exhibit that 

 increasingly active consensus of the sciences which charac 

 terizes their advancing development. Besides finding that 

 in these later times a discovery in one science commonly 

 causes progress in others ; besides finding that a great part 

 of the questions with which modern science deals are so mix 

 ed as to require the co-operation of many sciences for their 

 solution ; we find in this last case that, to make a single good 

 observation in the purest of the natural sciences, requires 

 the combined assistance of half a dozen other sciences. 



Perhaps the clearest comprehension of the interconnect 

 ed growth of the sciences may be obtained by contemplat 

 ing that of the arts, to which it is strictly analogous, and 

 with which it is inseparably bound up. Most intelligent 

 persons must have been, at one time or other, struck with 

 the vast array of antecedents pro-supposed by one of our 

 processes of manufacture. Let him trace the production 

 of a printed cotton, and consider all that is implied by it. 

 There are the many successive improvements through 

 w r hich the power-looms reached their present perfection ; 

 there is the steam-engine that drives them, having its long 

 history from Papin downwards ; there are the lathes in 

 which its cylinder was bored, and the string of ancestral 

 lathes from which those lathes proceeded; theie is the 

 steam-hammer under which its crank shaft was welded; 

 there are the puddling-furnaces, the blast-furnaces, the coal 

 mines and the iron-mines needful for producing the raw 

 material ; there are the slowly improved appliances by 

 which the factory was built, and lighted, and ventilated ; 

 there are the printing engine, and the die house, and the col 

 our laboratory with its stock of materials from all parts of 



