Although many attempts to make a seed drill had been made over millennia (the Chinese had developed a primitive implement in about 2500 BC) that made by Jethro Tull can still claim to be the first to work effectively. Tull (1674 to 1741) was an Oxford graduate who, because of bad health, went to live in the countryside, in Berkshire. He based his first drill on the shape of a wheelbarrow and followed it with several variations but kept a similar pattern for the seed-dropper, which was a revolving cylinder with regularly spaced holes that caught the seeds from the hopper above and dropped them into the open furrows. The drill that Tull devised could sow three rows of seed and was light enough to be drawn by a single horse. It was constructed almost entirely of timber and was carried on four wheels. The two large ones at the front carried the seed hopper and dropping device on their axle to feed the centre coulter. The smaller wheels carried two hoppers and mechanism to feed the two outer coulters. The coulters or hoes were arranged to pierce the soil below the machine and each had a channel cut into the back which directed the falling seed into the soil. Control of the flow of seed past the notched cylinder was achieved by means of a thin metal plate and a spring.