Child labor was common in West Virginia during the hand loading era, from the onset of coal mining in the 19th century until around 1930. Because mining was a skilled craft that took years to learn, boys often began part-time by going into the mine with a father or uncle, first perhaps on Saturdays and later during summer vacation, then spent more time in the mine and less in school as they grew older until they could work on their own. Boys working beside their fathers were not paid by the company or counted as employees, but received an allowance from their fathers' wages, which in 1910 were about 40 cents per ton mined. When considered ready, a boy might be given an independent job such as trapper boy, opening and shutting wooden ventilation doors for coal cars, a job that paid about one dollar per day in 1910. Older boys in their teens were assigned difficult and hazardous haulage work, including driving the mules or horses that pulled mine cars before electric or battery-powered motors were used. One of the most dangerous jobs was spragging, in which boys had to run beside moving mine cars and thrust a wooden sprag between the wheel spokes to slow or stop them, risking crushed limbs, amputated fingers and hands, or being run over. Laws attempted to regulate this labor: in 1887 West Virginia barred minors under twelve from working in factories, workshops, or mines; in 1907 it raised the minimum age to fourteen and banned females of any age from mine labor; and in 1919 it required minors to pass a physical examination, complete a sixth grade education, and limited those sixteen or younger to no more than eight hours of work a day. Yet enforcement was weak, as fathers could submit affidavits claiming a child was old enough and employers seeking cheap labor sometimes ignored the rules, and children continued working in southern West Virginia mines through the 1930s. In a sample of about 1,000 miners working in the early 1930s, more than forty-three percent had started before age seventeen, nearly sixteen percent between ages ten and fourteen, and two percent before age ten.