On the Economy of Machinery and Manufactures | Page 8

posterity, long after the
purposes of many of these records, as well as the names of their
founders, have been forgotten. The different degrees of force necessary
to move these ponderous masses, will have varied according to the
mechanical knowledge of the people employed in their transport; and
that the extent of power required for this purpose is widely different
under different circumstances, will appear from the following
experiment, which is related by M. Rondelet, Sur L'Art de Batir. A
block of squared stone was taken for the subject of experiment:
1. Weight of stone 1080 lbs
2. In order to drag this stone along the floor of the quarry, roughly
chiselled, it required a force equal to 758 lbs
3. The same stone dragged over a floor of planks required 652 lbs
4. The same stone placed on a platform of wood, and dragged over a
floor of planks, required 606 lbs
5. After soaping the two surfaces of wood which slid over each other, it
required 182 lbs
6. The same stone was now placed upon rollers of three inches diameter,
when it required to put it in motion along the floor of the quarry 34 lbs
7. To drag it by these rollers over a wooden floor 28 lbs

8. When the stone was mounted on a wooden platform, and the same
rollers placed between that and a plank floor, it required 22 lbs
From this experiment it results, that the force necessary to move a stone
along
Part of its weight
The roughly chiselled floor of its quarry is nearly 2/3 Along a wooden
floor 3/5 By wood upon wood 5/9 If the wooden surfaces are soaped
1/6 With rollers on the floor of the quarry 1/32 On rollers on wood 1/40
On rollers between wood 1/50
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