An illustration of a pneumatic trough, used by chemists to collect gases and invented by Stephen Hales (1677-1761). Hales, was an English clergyman who made major contributions to a range of scientific fields including botany, pneumatic chemistry and physiology. He was the first person to measure blood pressure and invented several devices apart from the pneumatic trough, including a ventilator and a surgical forceps for the removal of bladder stones. This image is from Vegetable Staticks (1727), which contains an account of experiments in plant physiology and chemistry.