joseph louis gay-lussac (1777-1850) and johann georg tralles (1763-1822) developed other means of measuring alcohol content. these units are usually measured in degrees, noted °gl, or °gt. the scale gay-lussac developed is almost equal to the abv scale described above. there may be slight different, because gay-lussac measured the alcohol content at 15° centigrade, and not 20°.