You can also check Tousard for measurement. He goes into some detail and conversion units and is a contemporary primary source.
As to being negligible, that depends on perspective. In French feet, Napoleon was five feet, two inches, which when careless authors used that as a direct translation, Napoleon was 'short.' If you convert it from French to English feet, he's about five feet six, which was average height for that day. Therefore, he wasn't 'short.'