Arthur Cobb Harvey invented a new spectrophotometer and received a patent for it in January, 1935. The patent was acquired by General Electric Co., who sold the first device in May of that year. A spectrophotometer is a photometer (a device for measuring the intensity of light) that measures intensity as a function of color. That is, it measures the wavelength of light. Harvey's was not the first to be invented. G.M.B. Dobson had created a spectrophotometer a decade earlier in order to investigate changes in atmospheric ozone, but it was not commercially. The GE spectrophotometer was much more sensitive; it could distinguish and chart some two million different shades of colour.