Louis Vauquelin

Louis Nicolas Vauquelin, a French chemist, was born May 16, 1763. In 1798, Vauquelin isolated a new element, chromium, from an ore called crocoite. Crocoite is mostly lead chromate and has a deep orange color (second image). Intrigued by the possibility of making a new pigment, by 1809 Vauquelin had learned how to produce a bright yellow powder, chrome yellow, which is lead chromate in a different form than found in crocoite…

Petrus Plancius

Petrus Plancius, a Dutch map and globe maker, died May 15, 1622; his date of birth is unknown. In the late 16th century, the Dutch began a series of trading voyages around Africa to the East Indies that would culminate in the founding of the Dutch East India Company in 1602. Navigation was initially difficult, because there were no accurate maps of the southern skies. In 1595, Plancius commissioned a pilot, Pieter Keyser, to record the position of as many southern stars as possible on a voyage to the Indies. Keyser catalogued about 130 stars, probably with the help of a colleague, Frederick de Houtman. Keyser died in 1596, before his return, but Plancius obtained the observations and proceeded to divide the southern stars up into 12 constellations…

Lorenzo Sitgreaves

Lorenzo Sitgreaves, a U.S. Army officer and explorer, died May 14, 1888; his age and date of birth are unknown. In 1849, a Topographical Engineer named James Simpson had led an expedition to survey the country west of Santa Fe, New Mexico. The Simpson survey got as far as the Zuni pueblo in western New Mexico before turning back. In 1851, Sitgreaves was ordered to continue the survey west, to the Colorado River and thence all the way to the Gulf of California. One person he inherited from the Simpson expedition was Richard H. Kern, an expedition artist…

Benjamin Thompson

Benjamin Thompson, better known as Count Rumford, an American-born British physical scientist, was born Mar. 26, 1753. Because he was a British sympathizer (and spy!) in his native Massachusetts and New Hampshire, Thompson was forced to flee to England, and although he came back during the Revolutionary War as commander of a British regiment, his American ties were effectively severed…

Ludwig Boltzmann

Ludwig Boltzmann, an Austrian physicist, was born Feb. 20, 1844. Boltzmann was a founder of what is called statistical thermodynamics. By assuming that a gas is made up of atoms moving with random velocities in all directions, he was able to predict large-scale (macroscopic) properties of the gas, such as its temperature and pressure, with great accuracy…