Stories from DEP is a collection of feature articles
published in DEP's internal newsletter, Weekly Pipeline.
This article was originally published May 10, 2011.
The Invention of the Sunflower That Thrives Without Sunlight
By the time Alfred Craven became a division engineer on the New Croton Aqueduct in 1884 he had already had a rich background in engineering, first as an engineer for the California State Geological Survey in 1871 and then as a tunnel engineer in the Comstock Lode silver mines of Nevada, where prospectors were looking to get rich quick. When Craven finally did move east to work on the New Croton Aqueduct, he brought with him years of practical experience working in dangerous environments, where imprecise calculations could cost workers their lives.
Craven also brought with him a legacy of family members who were well respected engineers. Most notable was his uncle, Alfred Wingate Craven, who served as Chief Engineer of the Croton Aqueduct from 1849-1868. A.W. Craven is best known for laying out much of the sewerage system of Manhattan and for working on the construction of the Central Park Reservoir. He also hosted the founding meeting of the American Society of Civil Engineers (and Architects) in the Croton Aqueduct Department offices on November 5, 1852.
As construction began on the New Croton Aqueduct Tunnel, Craven faced many challenges including an inability to get precise measurements of the cross sections of tunnels in order to estimate the amount of rock removed, and how much lining material was needed. It was clear that a solution was needed since measurements were taken every 10 feet throughout the 30 miles that the tunnel stretched. That solution came in the form of the “Sunflower Instrument,” which Craven invented and had manufactured in 1887. Essentially, it consisted of a yellow, wooden disc mounted on a tripod with a rest for a removable measuring pole. The disc is graduated in degrees and the measuring pole is marked with feet and tenths.
In 1895, Craven was placed in charge of the construction of Jerome Park Reservoir but left in 1900 to work with the Rapid Transit Commission, the entity in charge of creating the first subway system in New York City. The sunflower instrument was widely used during construction of subway tunnels, where Craven was in charge of making sure work was being done safely and accurately. He became best known for helping with the development of the Lexington Avenue subway line and the initial subway line for Brooklyn.
Although Craven was no longer working on the water supply, the tool continued to be used and by 1909 the Board of Water Supply put out a bid to have 13 of them custom built. The specifications give precise details including the stipulation that they be made of durable material that can withstand arduous conditions. Despite their durability, damage to the instruments was common and the cost of repairing them became too high. Eventually, the tools became less important as measurements were instead taken from the wooden forms used to support the tunnels during construction. By 1934, during construction of City Water Tunnel No. 2, the tool was only being used to take measurements from tunnels that did not use support frames and broken or missing parts stopped being replaced, until they fell out of use completely. A complete example of the “Sunflower Instrument” survives today in the DEP Archives collection.