Thirdly, and lastly, the machines and instruments of trade, etc. which compose the fixed capital, bear this further resemblance to that part of the circulating capital which consists in money; that as every saving in the expense of erecting and supporting those machines, which does not diminish the introductive powers of labour, is an improvement of the neat revenue of the society; so every saving in the expense of collecting and supporting that part of the circulating capital which consists in money is an improvement of exactly the same kind.