The ozone layer was discovered in 1913 by French physicists Charles Fabry and Henri Buisson. Its properties were explored in detail by the British meteorologist G. M. B. Dobson, who developed a simple spectrophotometer, the Dobsonmeter. This tool could be used to measure the ozone levels found in the stratosphere from the ground. Between 1928 and 1958 Dobson established a worldwide network of ozone monitoring stations. Most of these stations are still in use today. The "Dobson unit", a convenient measure of the total amount of ozone in a column overhead, is named in his honor.