In 1888, a 32-year-old MIT professor poured a glass of water, held it up for a class of young civil engineers to see, and over the course of an hour struck terror in the hearts of his listeners.
“He would scare us to death by saying that [the water] contained enough germs of typhoid fever to give the disease to a thousand people,” wrote former student George C. Whipple. The professor then eased tensions by showing how engineering methods could be used to make water safe to drink.
William Thompson Sedgwick—the passionate MIT biology department head better known as “The Chief” to his students—saw the science of tracking and eradicating waterborne bacteria as a matter of life and death. “Sanitation belongs in schools of engineering,” said Sedgwick, who became one of the main forces behind the sanitary engineering curriculum at MIT (see also “Dirty Water,” in the November/December 2013 issue of MIT News). Just one year after frightening budding engineers with his water of doom, Sedgwick had the perfect research opportunity to show the world exactly what he meant.
In the late 1800s, Lawrence, Massachusetts, attracted flocks of German, French-Canadian, and Irish immigrants thanks to its burgeoning textile mills along the Merrimack River. In the 1870s, the Essex Company, in conjunction with the Massachusetts Board of Health, set up a small water and sewage treatment facility to prevent solid industrial waste from leaking into the town’s water supply. When a severe typhoid epidemic broke out in the town a decade or so later, the facility was the perfect place for a team of scientists led by Sedgwick to prove that disease can travel by water and that a medical degree wasn’t required to stop it. It became the Lawrence Experiment Station.
Before addressing those structural concerns, however, Sedgwick’s team first needed a way to calculate how prevalent waterborne organisms were in the Merrimack. The first step was to figure out a better method of counting the cells that live in liquid. Before 1889, scientists relied on the “cloth method”—a system in which water was filtered through a cloth to catch organisms living on the surface. That evolved into the conceptually similar “sand method,” which substituted fine-grained sand for cloth, but neither was particularly effective at helping scientists get accurate cell counts.
One year after beginning work at the Experiment Station, Sedgwick partnered with civil engineer George W. Rafter and pioneered the Sedgwick-Rafter method, which used a sand filtration system to isolate water-dwelling organisms and a specially marked glass disc placed on top of the microscope’s eyepiece to make cell counting easier. Better known as an ocular micrometer, this disc was engraved with a small, square grid, which created a manageable area for counting cells and an easy way for researchers to extrapolate the number of cells in a given sample.
With the new method in place, Sedgwick’s researchers analyzed water samples from across Massachusetts, eventually tracing typhoid outbreaks in Lawrence and nearby Lowell to river pollution. “The proportion of sewage that has been directly mingled with the water of the Merrimack River is, at the time when it arrives at Lowell, about one part of sewage in every 1,200 parts of water,” Sedgwick wrote in an 1891 report to the Water Board of Lowell. “That is equivalent to about a thimbleful of sewage in every quart of city water.”
To prove that the outbreak could be stopped through engineering rather than medical treatment, Sedgwick’s team encouraged Lawrence legislators to build a citywide water filtration system, the first of its kind in the nation. Implemented in 1893 despite significant legislative resistance, the filtration system reduced instances of typhoid fever by nearly 50 percent, according the Journal of the American Medical Association, and established Lawrence as the first town in the United States to filter water for disease prevention.
The success at Lawrence not only set water filtration standards in locales across the globe; it also laid the foundation for a brand-new field of study that examined health issues through the lens of strategic planning and engineering. Sedgwick spent the rest of his life expanding this field, in no small part through his work cofounding what is now the Harvard School of Public Health—an institution launched in partnership with his once-terrified student George C. Whipple.
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