§ 2. In modern machinery a larger and larger amount of inventive skill is engaged in adjusting machine-tending to the physical and mental capacity of women and children. The evolution of machinery has not moved constantly in this direction. In cotton-spinning, for example, the earlier machines--Hargreave's jennies and Arkwright's water-frames--were generally worked by women and children, the women who had been engaged in the use of the older instruments--the distaff, spindle, hand-wheel--coming into the mills. But the growing complexity and size of the mule made it too cumbrous for women and children, and spinning for a while became a male occupation in England. In the United States the difficulty of procuring male labour stimulated the invention of the ring spinning-frame, some sixty years ago, which could be worked by woman's labour. The limitations and imperfections of this mode of spinning retarded its adoption in England for upwards of half a century. But recent improvements have led to a rapid increase of the adoption of the ring-frame in Lancashire. In the low medium and low counts it is rapidly displacing the mule, and in countries where fine counts are little spun it will probably be the dominant machine.[244] In Lancashire it does not, however, seem at all likely to be rendered capable of displacing the mule in finer counts. The ring-frame throws spinning once more into the hands of women and of children, who in some Lancashire towns are quickly displacing the labour of the men.