10.  Of tools.  The difference between a tool and a machine is not capable of very precise distinction; nor is it necessary, in a popular explanation of those terms, to limit very strictly their acceptation.  A tool is usually more simple than a machine; it is generally used with the hand, whilst a machine is frequently moved by animal or steam power.  The simpler machines are often merely one or more tools placed in a frame, and acted on by a moving power.  In pointing out the advantages of tools, we shall commence with some of the simplest.

11.  To arrange twenty thousand needles thrown promiscuously into a box, mixed and entangled in every possible direction, in such a form that they shall be all parallel to each other, would, at first sight, appear a most tedious occupation; in fact, if each needle were to be separated individually, many hours must be consumed in the process.  Yet this is an operation which must be performed many times in the manufacture of needles; and it is accomplished in a few minutes by a very simple tool; nothing more being requisite than a small flat tray of sheet iron, slightly concave at the bottom.  In this the needles are placed, and shaken in a peculiar manner, by throwing them up a very little, and giving at the same time a slight longitudinal motion to the tray.  The shape of the needles assists their arrangement; for if two needles cross each other (unless, which is exceedingly improbable, they happen to be precisely balanced), they will, when they fall on the bottom of the tray, tend to place themselves side by side, and the hollow form of the tray assists this disposition.  As they have no projection in any part to impede this tendency, or to entangle each other, they are, by continually shaking, arranged lengthwise, in three or four minutes.  The direction of the shake is now changed, the needles are but little thrown up, but the tray is shaken endways; the result of which is, that in a minute or two the needles which were previously arranged endways become heaped up in a wall, with their ends against the extremity of the tray.  They are then removed, by hundreds at a time, with a broad iron spatula, on which they are retained by the forefinger of the left hand.  As this parallel arrangement of the needles must be repeated many times, if a cheap and expeditious method had not been devised, the expense of the manufacture would have been considerably enhanced.

12.  Another process in the art of making needles furnishes an example of one of the simplest contrivances which can come under the denomination of a tool.  After the needles have been arranged in the manner just described, it is necessary to separate them into two parcels, in order that their points may be all in one direction.  This is usually done by women and children.  The needles are placed sideways in a heap, on a table, in front of each operator, just as they are arranged by the process above described.  From five to ten are rolled towards this person with