Ricardo on machinery. What matters: technical progress or substitution of machines for circulating capital?

Ricardo’s argument on machinery seems to deal both with technical progress and with the substitution of machines for circulating capital. However, they produce different effects, which are to be distinguished and analysed. Two models are introduced: in the first model, there is technical progress and no machines; in the second, there is substitution of machines for labour and no technical progress. Both short-run and long-run effects are examined