Biography of Nicolas Lacaille

Biography of Nicolas Lacaille

    Nicolas Lacaille was a French-born observational astronomer. He is most famous for his expedition to the Cape of Good Hope, where he named 14 southern constellations. The names he assigned are still in use today, and he is known for his work as “the father of southern astronomy.”
    Lacaille was born on the 15th of March, 1713, in the French town of Rumigny, near the city of Reims. Both his mother, Barbe Rubuy, and father, Luis de la Caille, were descended from distinguished families (though Nicolas never really investigated his heritage). At a young age, Lacaille demonstrated a strong academic ability, and his father saw to it that in 1729, Nicolas attended the prestigious Collège de Lisieux in Paris. There he studied rhetoric, and developed his habit of wide reading. He first developed his interest for astronomy and mathematics after discovering the works of Euclid. After his graduation, he continued to pursue astronomy, and in 1736 he contacted J.P. Grandjean de Fouchy, the secretary at the Academy of Sciences. Fouchy, amazed at Lacaille’s extensive knowledge of astronomy, introduced him to Jacques Cassini, head of the astronomical observatory in Paris. Lacaille went to live at the observatory, and made his first astronomical observation in May 1737.
    Lacaille’s knowledge of astronomy led him to jobs regarding navigation and geodetics. Lacaille was tasked with mapping the seacoast from Nantes to Bayonne. He was also asked to take geodesic measurements to help settle the argument over the shape of the earth. He was able to demonstrate that degrees of terrestrial latitude increased away from the poles, supporting the Newtonian theory of a bulge at the equator. For this work, he was accepted into the Academy of Sciences in 1741 as an astronomer.
    In 1746, Lacaille moved from the observatory in Paris to the observatory at the College de Lisieux. There, he observed the sky prolifically, and recorded astronomical phenomena such as conjunctions, lunar occultations, and comets. Lacailles became curious about stars he could not view: those only visible in the southern hemisphere. He proposed an expedition to the Cape of Good Hope in South Africa, and on October 21st 1750, he departed from Paris on his journey. He set sail from France a month later on a ship known as the Glorieux. The vessel finally arrived at the cape on March 30th 1751 (after having to stop in Brazil for repairs). Lacaille made plans to determine the longitude of the cape by measuring the parallax of the sun and moon. He also planed to chart all the visible stars to around the 4th magnitude. He ended up exceeding his own expectations. From August of 1751 to August of 1752, he undertook 110 observing session of 8 hours each, including 16 full nights. Using only his small eight-power telescope, he mapped almost 10,000 stars of the southern hemisphere.
    When he returned to Paris, he was greatly lauded for his accomplishments. He went on to publish, among other books of other subjects, a catalogue of 1,942 of the stars he observed. In 1757, he also published Astronomiae Fundamenta, (today a very rare work) detailing positions of 400 bright stars. Lacaille died in 1762 from an illness he contracted while in Africa. Some say the rigorous observation routine he imposed on himself was the chief reason he contracted the disease.