In the late 1950s, Mary Ellen Avery was a research fellow in Jeremiah (“Jere”) Mead’s lab at Harvard School of Public Health, with Clement Smith as her clinical supervisor. She was working nights in the delivery room at the Boston Lying-In, where she saw many premature babies with hyaline membrane disease (now called respiratory distress syndrome, or RDS) struggle to breathe. She had access to the lungs of babies who died of RDS, and noticed that these babies had no residual air in their lungs at autopsy – as though they’d been unable to keep the air spaces in their lungs open. Having read in her studies that lungs are able to retain air due to low surface tension, she wondered if the surface tension in the lungs had something to do with it.

Letter to John Clements, 1958

Avery was inspired by a 1957 article by John Clements which examined the effects of nerve gases on the lungs by measuring surface tension. Clements used a modified Wilhelmy balance, a device that has been around since the late 1800s, to measure surface tension in the lungs. Avery soon visited Clements at the U.S. Army Chemical Center in Edgewood, Maryland, to learn how to build her own version of the device.

In a letter to Clements in 1958 (pictured at right), Avery said:

"As I expect you have heard, I have been pecking away at surfaces this summer. The results are fun (Jere's word is spurious), but at any rate, I would like to talk with you about them."