Rather than low wages, efficiency and scale, Birmingham's manufacturing growth was fuelled by a highly skilled workforce, specialisation, flexibility and, above all, innovation. The low barriers to entry to the Birmingham trades gave the town a high degree of social mobility and a distinctly entrepreneurial economy; the contemporary William Hutton described trades that "spring up with the expedition of a blade of grass, and, like that, wither in the summer". In terms of manufacturing technology Birmingham was by far the most inventive town of the era: between 1760 and 1850 Birmingham residents registered over three times as many patents as those of any other town or city. Despite the landmark inventions of engineers such as James Watt, most of these developments are better characterised as part of a continuous flow of small-scale technological improvements. Matthew Boulton remarked in 1770 how "by the many mechanical contrivances and extensive apparatus wh we are possess'd of, our men are enabled to do from twice to ten times the work that can be done without the help of such contrivances". Innovation also took place in production processes, particularly in the development of an extreme division of labour. Contemporary sources noted that in Birmingham even simple products such as buttons would pass through between fifty and seventy different processes, performed by a similar number of different workers. The resulting competitive advantage was noticed by Lunar Society member Richard Lovell Edgeworth when he visited Paris, observing that "each artisan in Paris ... must in his time 'play many parts', and among these many to which he is incompetent", concluding that "even supposing French artisans to be of equal ability and industry with English competitors, they are left at least a century behind".