Ever since Galileo used the first refracting telescope to observe the moon in 1609, scientists have expanded their knowledge of the skies. Telescopes have increased our ability to see what the naked eye cannot. Centuries later, in Massachusetts, Alvan C. Clark and his sons, Alvan Graham Clark and George Bassett Clark began making refracting telescopes. Alvan C. Clark was already a successful portrait painter but became interested in telescopes after assisting his son George in a school project. The rest, as they say, is history.
Alvan Clark’s reputation for high quality lenses grew quickly. He was famously proficient at figuring near-perfect lenses. Much of the final polishing was done by hand and Clark was said to be able to spot tiny imperfections by touch alone. His company, Alvan Clark and Sons, produced over 500 telescopes in the years from 1844 through 1897.
They were well known for producing the world’s largest lenses at the time. One of Clark’s most famous telescopes is the Dearborn telescope. The original mounting and tube are part of the Adler’s permanent collection and are exhibited in Telescopes: Through the Looking Glass. The lens itself is still used at the Dearborn Observatory at Northwestern University. Clark and Sons continued to outdo themselves, building bigger and better telescopes. They still hold the record for the world’s largest refracting telescope, in use at the Yerkes Observatory in Wisconsin.
In addition to building renowned telescopes, the Clarks contributed to observational astronomy, often while testing their lenses. Alvan Graham Clark discovered the first ever seen white dwarf star, a companion of Sirius, as well as many double stars. They experimented with early astronomical photometry and photographed solar eclipses.
I recently interned in the Adler’s Webster Institute for the History of Astronomy, arranging, describing, and digitizing the Alvan Clark and Sons Business and Family Papers. The Alvan Clark collection includes a great deal of personal papers, mostly handwritten letters between family members and friends. Clark’s wife Maria traveled extensively and wrote letters home. Her correspondence reads like a travelogue of interesting places in the United States and abroad. The collection of professional and personal papers, as well as photographs, reminds us of a past, elegant age by highlighting one family’s dedication to its craft. Their telescopes and lenses are examples of remarkable scientific and engineering achievements and the archival collection at the Webster Institute allows us to experience this amazing time.
Written by Pamela Ruos, archives intern at the Adler Planetarium.