Having traced the general nature of instruments, and shown, that the relations existing among the circumstances by which they are affected, make it practicable to arrange them in a regular series, the object next claiming our attention, is, to ascertain the causes determining the amount of them which each society possesses, and to mark the more remarkable phenomena which the operation of those causes produces.
The causes determining the amount of instruments, formed by any society, will, I believe, be found to be four.
1.The quantity and quality of the materials owned by it.
2.The strength of the effective desire of accumulation.
3.The rate of wages.
4.The progress of the inventive faculty.
The nature of the second of these, and the circumstances on which its strength depends, will form the subject of the next chapter, but previously to entering on it, it is necessary to establish the following proposition.
The capacity which any people can communicate to the materials they possess, by forming them into instruments, cannot be indefinitely increased, while their knowledge of their powers and qualities remains stationary, without moving the instruments formed continually onwards in the series A B C etc., but, there is no assignable limit to the extent of the capacity, which a people having attained considerable knowledge of the qualities and powers of the materials they possess, can communicate to them, without carrying them out of the series A B C etc., even if that knowledge remain stationary.
The capacity of instruments may be increased, by adding to their durability, or to their efficiency; that is, by prolonging the time during which they bring to pass the events, for the purpose of effecting which, they are formed, or, by increasing the amount of them which they bring to pass within the same time.
A dwelling-house is an instrument, aiding to bring to an issue events of various classes.It more or less completely prevents rain, damp, and the extremes of cold and heat, from penetrating to the space included within its area.It preserves all other instruments contained within it, in comparative safety.It gives those who inhabit it the power of carrying on unmolested, various domestic occupations, and of enjoying, undisturbed by the gaze of strangers, any of the gratifications or amusements of life, of which they may be able and desirous to partake.Events of these sorts, it may bring to pass, for a longer or shorter time, or to a greater or less extent, within the same time.In the former ease, the durability is increased, in the latter, the efficiency; in both, the capacity is augmented.Dwelling-houses are built of different.materials, and those materials are wrought up with more or less care.A dwelling might be slightly run up of wood, lath, mud, plaster, and paper, which would only be habitable for a few months or years, like the unsubstantial villages, that Catherine of Russia saw in her progress through some parts of her dominions.Another of the same size, accommodation, and appearance, that might last for two or three centuries, might be constructed, by employing stone, iron, and the most durable woods, and joining and compacting them together, with great nicety and accuracy.Between these two extremes there are all imaginable varieties.According to that adopted, both the durability and the efficiency will be greater or less.These two may be separated from each other, at least in imagination, and therefore we may consider them apart.
If the increased durability that may be given an instrument be considered apart from the increased efficiency that will also probably be communicated to it, it must be regarded simply as an extension of its existence, and consequently as a like extension of its capacity.A dwelling-house lasts, we shall say, sixty years, but in other respects is perfectly similar to one lasting only thirty years.Considered as an instrument, the former is, therefore, exactly equal to two of the latter, the one formed thirty years after the other.A house lasting one hundred and twenty years would in like manner have the capacity of four houses, one formed now, a second thirty, a third sixty, and a fourth ninety years hence.The capacity thus increasing at the same rate as the duration, if the limits to the power of giving durability be indefinite, the limits to the power of communicating capacity are also indefinite.
