It’s visible from all over campus and draws the eye as you walk across College Walk. The dome of Low Library stands tall and proud in the center of everything. Have you ever wondered what is the dome made of? How high is it? How can you get up there? And is it safe? In this week’s installment of #WeMissLow, we take a look inside the dome of Low Memorial Library.
The dome of Low Library is constructed entirely of masonry. There is no steel superstructure. It is built completely out of bricks, covered or sheathed with Indiana limestone panels. The Low Library dome is the largest such structure of its kind in the United States. Standing 135 feet high, the 100-foot wide dome is built in steps, which start at 4-feet thick at the base and taper to 9 inches at the crown. The arches beneath the dome not only carry the weight of the dome but also light the interior rotunda. The dome, however, is made up of a pair of domes: one on the outside and one on the inside. 105 feet above the rotunda floor, there is a 70-foot wide inner dome, painted in a dark sky blue. This inner dome is made out of plaster on an iron frame.
There used to be designated hours when visitors could climb the steps in between the inner and outer domes and reach the roof or the top of the library dome. One of those intrepid visitors was University Extension pre-med student Amelia Earhart.(Here photographed sitting at the top of the dome in 1920 and, more clearly, here.) In 1933 Earhart recalled, “The first adventure I had at Columbia was in the air. I climbed to the top of the Library and then I descended into the intricate tunnels.” In 1925 University President Nicholas Murray Butler watched a solar eclipse from the top of the Low Library dome. Students watched from the east windows of Hartley and Livingston (now Wallach) Halls, the top floor of Journalism and the roofs of fraternities, while fifty thousand eclipse-watchers crowded along Morningside Drive. Unfortunately, the dome is no longer open to visitors.
So, is it safe? In 1920, when the builder of Low Library, Orlando Whitney Norcross, passed away, the local paper noted his struggles to get the New York City engineering department to approve the building plans. Not only was the dome safe, during Norcross’s lifetime, the dome never leaked. During the Cold War era, the Columbia Council on Civil Defense examined Low Library to see if the building could be used as a shelter area. The investigation revealed that the dome built “with an interlocked, self-supporting type of construction” would withstand a vertical thrust, but an atomic blast would collapse the dome, which would fall and “go through everything beneath it until it reached bedrock.”  In 1999 the University hired Helpern Architects to modernize Low’s infrastructure and renovate parts of the building. As part of this work, they conducted tests that certified that 100 years later, the dome is quite safe and stable.  They also captured some great photographs, including one of the inside in between the domes.
 Memorandum to Dr. White re: Hazard of Low Memorial Dome, 1951 January 15. Buildings and Grounds collection (Box 11, Folder 2). University Archives, Rare Book & Manuscript Library, Columbia University Libraries.
 Linn, Charles. “Non-destructive Testing Probes Dome’s Safety.” Architectural Record, March 2003, Volume 191 Issues 3, 181.