ALEXANDER HUMBOLDT, German naturalist and traveler, born (d: 1859). This is one of my personal favorite discoveries in the development of this LGBT history project. One of the geniuses of the 19th century, he made so many contributions to science there is no way to do justice to him in this space.
From 1799 to 1804 he made an expedition with A.J. A. Bonpland to Central and South America and Cuba a journey reputed to have laid the foundations for the sciences of physical geography and meteorology. Humboldt explored the Orinoco and Amazon. He ascended the Andean peaks of Peru to study the relation of temperature and altitude, made observations leading to the discovery of the periodicity of meteor showers and the fertilizing properties of guano.
In 1808 he settled in Paris and published his findings in 23 volumes. During this period, he also established the use of isotherms; studied the origin and course of tropical storms, the increase in magnetic intensity from the equator to the poles, volcanology and pioneered the investigation of the relationship between geographical environment and plant distribution. All this before middle age. He was extraordinarily handsome according to pictures rendered of him throughout his lifetime.
He was always thought to be homosexual, with the rumors having begun with the suspicion that he and Bonpland were lovers. What was suspected seemed to be confirmed in the minds of his contemporaries when he named his valet Seifert as his sole heir.