Economy of Machinery and Manufactures. 115 



ed crust on the edges of the block. The consumption of ink by the 

 new system of machine printing, is to that by the balls, or old method, 

 as four to nine, or rather less than half. There is a saving, also, in 

 the disuse of " the set-off sheet," which, in the old mode, received 

 every printed sheet, to guard it from being soiled, and to absorb the 

 superfluous ink. In the best kind of printing, in the old method, it 

 was necessary to change it once in twelve times, as it became too 

 much soiled for further use. In the new, a blanket is employed as 

 a substitute, and so little in amount is the superfluous ink, that it is 

 changed only once in two thousand, and in common printing once in 

 five thousand times.* 



" The accuracy with which machinery executes its work, is one of 

 its important advantages," but equally important is the saving of time ; 

 for improved tools increase the quantity of work performed in a given 

 time. It would require a long time for a skilful workman with files 

 and polishing substances to form an accurate cylinder of a piece of 

 steel, but by the use of the lathe and the sliding rest, it is quickly and 

 cheaply accomplished. The art of turning is one of the most beau- 

 tiful processes, and, with the exception of copying, is perhaps one 

 of the most accurate of mechanical operations : for example, if the 

 top of a circular box is to be made to fit over the lower part, it may 

 be done by gradually advancing the tool of the sliding rest until the 

 proper degree of tightness between the box and the Hd is ascertained. 

 After this adjustment, if a thousand boxes are made, no additional 

 care is required ; the same identity pervades them all. Equally 

 exact are all the arts of printing. The impressions to the most mi- 

 nute traces in the same block or copper-plate, have a similarity, which 

 no labor could produce by hand. 



The author's estimate of the value of copying in the arts, will be 

 seen from the following extracts, which, although abridged, are prin- 

 cipally in his own language. 



A principle which pervades a large portion of all manufactures, 

 and one upon which the cheapness of the articles produced seems 

 greatly to depend, is copying, taken in hs most extensive sense. 

 Almost unlimited pains are, in some instances, bestowed on the ori- 

 ginal, from which a series of copies is to be produced ; and the larger 

 the number of these copies, the more care and pains can the manu- 

 facturer afford to lavish on the original. It may thus happen, that 



* See p. 47, Economy of Machinery. 



