At each increase of knowledge, as well as on the contrivance of every new tool, human labour becomes abridged.  The man who contrived rollers, invented a tool by which his power was quintupled.  The workman who first suggested the employment of soap or grease, was immediately enabled to move, without exerting a greater effort, more than three times the weight he could before.(5*)

6.  The economy of human time is the next advantage of machinery in manufactures.  So extensive and important is this effect, that we might, if we were inclined to generalize, embrace almost all the advantages under this single head:  but the elucidation of principles of less extent will contribute more readily to a knowledge of the subject; and, as numerous examples will be presented to the reader in the ensuing pages, we shall restrict our illustrations upon this point.

As an example of the economy of time, the use of gunpowder in blasting rocks may be noticed.  Several pounds of powder may be purchased for a sum acquired by a few days’ labour:  yet when this is employed for the purpose alluded to, effects are frequently produced which could not, even with the best tools, be accomplished by other means in less than many months.

The dimensions of one of the blocks of limestone extracted from the quarries worked for the formation of the breakwater at Plymouth were 26 1/2 ft long, 13 ft wide, and 16 ft deep.  This mass, containing above 4,800 cubic feet, and weighing about 400 tons, was blasted three times.  Two charges of 50 lbs each were successively exploded in a hole 13 feet deep, the bore being 3 inches at top and 2 1/2 inches at bottom:  100 lbs of powder were afterwards exploded in the rent formed by those operations.  Each pound of gunpowder separated from the rock two tons of matter, or nearly 4,500 times its own weight.  The expense of the powder was L 6, or nearly 7 1/2d. per lb:  the boring occupied two men during a day and a half, and cost about 9s.; and the value of the produce was, at that time, about L 45.

7.  The simple contrivance of tin tubes for speaking through, communicating between different apartments, by which the directions of the superintendent are instantly conveyed to the remotest parts of an establishment, produces a considerable economy of time.  It is employed in the shops and manufactories in London, and might with advantage be used in domestic establishments, particularly in large houses, in conveying orders from the nursery to the kitchen, or from the house to the stable.  Its convenience arises not merely from saving the servant or workman useless journeys to receive directions, but from relieving the master himself from that indisposition to give trouble, which frequently induces him to forego a trifling want, when he knows that his attendant must mount several flights of stairs to ascertain his wishes, and, after descending, must mount again to supply them.  The distance to which such a mode of communication can be extended, does not appear to have been ascertained, and would be an interesting subject for enquiry.  Admitting it to be possible between London and Liverpool, about seventeen minutes would elapse before the words spoken at one end would reach the other extremity of the pipe.