Since its founding in 1891, many people have passed through the doors of the Vatican Observatory. A quick perusal of our guestbook reveals several Names, including Popes, nobel laureates, astronauts, actors, and saints.
Today's guestbook entry is from June 20, 1910, when Arthur Day made a visit.
Next to his name, Arthur Louis Day (1869-1960) wrote, "Geophysical Laboratory, Washington D.C."
In 1907, Arthur Day became the first director of the Geophysical Laboratory of the Carnegie Institution in Washington D.C. The founding of the laboratory was a direct result of his research on rock-forming minerals while he was with the U.S. Geological Survey. He is most noted for research on the isomorphism and thermal properties of feldspars.
He also contributed research in vulcanology, seismology and geothermal energy.
He was vice president of the National Academy of Science from 1933-1941, and became president of the Geological Society of America in 1938.
In 1941, the Geological Society of London awarded Day the Wollaston Medal, its highest honor.
In 1948, Day endowed an award (the Arthur L. Day award) presented annually by the Geological Society of America for distinction in the application of physics or chemistry to solving geologic problems.
The U.S. National Academy of Sciences presents triennially the Arthur L. Day Prize and Lectureship named in his honor.
[Edit: Thanks to a helpful comment from a reader, there is a small correction. In the original version, I stated that Day received the Wollaston Medal from the Geological Society of America. It was in fact awarded by the Geological Society of London.]