Tacoma’s rainmaker: The search for a UPS professor’s long-lost invention

Nichole Hine, a research intern at the Tacoma Historical Society, shows a 1947 photo of College of Puget Sound’s Robert Sprenger with a rainmaking machine he built.
Nichole Hine, a research intern at the Tacoma Historical Society, shows a 1947 photo of College of Puget Sound’s Robert Sprenger with a rainmaking machine he built. phaley@thenewstribune.com

While working as a research intern at the Tacoma Historical Society, Nichole Hine was surprised to discover a rainmaking machine.

Or at least an old black and white photograph of one.

Hine, 21, was checking the archives of the Tacoma Public Library when she came across the photo, one of the first she’d found while working on an upcoming exhibit about Tacoma inventors.

The photo, depicting the machine’s inventor loading the suitcase-sized metal device onto a plane, did not give much in the way of clues regarding the machine’s current location.

Even more surprising to Hine was that the inventor, Robert Sprenger, hailed from the school she’ll be graduating from in December, the University of Puget Sound.

In the 1940s, Sprenger was a chemistry professor at what then was known as the College of Puget Sound and worked on inventions as well.

“I’d never heard of any sort of invention to come out of UPS,” she said.

Hine ventured into the university’s online archives, discovering more information about the machine in an article Sprenger wrote for a 1948 UPS alumni magazine.

In the article, Sprenger explained the science behind rainmaking and reported on tests of the machine in the Prosser area in 1947.

The “vapor generator,” once strapped to a plane and flown into the sky, would seed “finely divided particles of silver iodide, in the form (of) an invisible vapor” into the clouds.

The particles would freeze in the clouds as snow and, during their fall to earth, turn into rain.

The machine had been commissioned by G.A. Sampson, a UPS alumnus and a wheat broker who hoped it would help in “semidry wheat-growing areas in eastern Washington.”

Hoping to find the machine for the inventors display, Hine contacted UPS officials and asked whether they knew where it could be.

None of her findings gave her any other clues about where the machine might have ended up.

“I really haven’t been able to find very much … at all,” she said. “That’s the problem, it’s just very obscure.”

The university posted about the search on its Facebook page on June 15.

Some commenters joked that a rainmaking machine wasn’t exactly necessary in soggy Tacoma while others suggested places on campus where it might be hidden, including the university archives.

Katie Henningsen, an archivist at UPS, said she’s received at least eight calls in the past couple months from people asking about the long-lost device.

So far, she said, the search hasn’t turned up anything.

But the newfound publicity for the machine’s inventor did catch the attention of his daughter, Sally Sprenger.

While she didn’t know where the invention could be, she said she faintly remembers when her father had been working on “the machine for feeding clouds.”

“I always remember he had a little office, his little inventing studio,” said Sally Sprenger, 69. “That’s where he worked out his projects.”

The studio, once in the 3500 block of Sixth Avenue, since has been replaced by the record store, Golden Oldies.

The rainmaking machine was far from the only invention created by Robert Sprenger, who died at 53 from diabetes-related kidney failure.

Sally Sprenger said that when her chemistry-professor dad wasn’t busy teaching, he was experimenting and working on inventions. His shirt was often covered in small holes caused by chemical burns from his experiments.

“He always smelled of chemicals,” said his daughter, who now lives in France after working at UPS’ Study Abroad office. “It’s a smell that I’ve always loved.”

Her father’s inventions weren’t confined to his lab or even his room. They were all around the house, which often smelled of formaldehyde, rubber and the almondlike scent of a cleaning product he created and used.

While Sally Sprenger and her younger sister, Cynthia (Sprenger) Mooney, were growing up, their dad worked on a special foam rubber, leaving pieces of the test material littered across the household.

However much Sprenger loved his inventions, he devoted most of his time to his students. Sally Sprenger said he felt called to teach, even though he wanted to be a researcher.

“Despite the fact that in his deepest heart’s wish he wanted to do research, he channeled all those longings into being a great professor,” she said.

Sprenger’s ability to teach was hurt when his diabetes worsened, leaving him increasingly unable to see. On nights in the Sprenger household, the sisters had two options: help their mother cook dinner or read chemistry textbooks to their father, who no longer could do so himself.

“I was maybe in fourth grade, so he was in his mid-30s when he started losing his vision,” Sally Sprenger said.

Still, Sprenger continued teaching until his death in 1970.

UPS continues to remember him during the annual Chemistry Department picnic, where two awards are given in his name: the Robert Sprenger Science Scholarship Award and the Sprenger Memorial Scholarship.

Curt Mehlhaff, who worked with Sprenger at UPS from 1968 until his death two years later, tells stories about him at the picnic each year.

Back in the day, Mehlhaff was a 28-year-old professor of analytical chemistry. He remembers walking into his office early each morning and seeing Sprenger’s wife, Mae, reading to her husband, whose office was directly across from his own.

“She would be prepping him on his organic chemistry lecture for that morning because his eyesight was so poor he couldn’t read his own lecture notes,” said Mehlhaff, 76. “That would happen every morning.”

Despite his challenges, Sprenger was active throughout his life, said Mooney, who lives in Portland.

That’s the dad she remembers most.

“Everything he did was pretty remarkable,” said Mooney, 63. “I remember him making furniture and building things, so somehow or another he was able to figure out how to work around his disability.

“Really, up until really close to when he died we were still boating on our sailboat.”

As for Sprenger’s rainmaker, did it work? No reports anyone has found attest to whether the tests in Prosser were successful.

“Of the several articles I read about it, there was never any mention whether or not it was successful,” Sally Sprenger said.

“There were so many things that Dad did simply for the pleasure of doing them.”


Manola Secaira: 253-597-8876

If you can help

Nichole Hine’s internship with the Tacoma Historical Society will conclude at the end of July. However, others will continue to work on the society’s inventions exhibit until its unveiling Nov. 29.

Anyone with information about Robert Sprenger’s rainmaking machine or other inventions by Tacomans is asked to contact the Historical Society at 253-472-3738.

Does cloud-seeding work?

Experiments in cloud-seeding suggest that it may be possible to artificially create rainfall.

Rainfall occurs when supercooled droplets of water — those that are still liquid but are at a temperature below the usual freezing point of zero centigrade — form ice crystals.

Now too heavy to remain suspended in the air, these then fall, often melting on their way down to form rain.

Even in dry areas,the air usually contains some water. This can be made to come together and form ice crystals by seeding the atmosphere with chemicals such as silver iodide or dry ice.

They work to promote rainfall by inducing nucleation — what little water is in the air condenses around the newly introduced particles and crystallizes to form ice.

The “seeds” can be delivered by plane or simply by spraying from the ground.

But does it work?

It’s hard to tell for sure. As is often the case with weather and climate, it’s impossible to carry out a controlled experiment — so, in areas of increased precipitation, we can’t know whether it would still have rained even if the clouds hadn’t been seeded.

Success has been claimed for trials in Australia, France, Spain and the United States. In the United Arab Emirates, the technique is credited with creation of 52 storms in the Abu Dhabi desert, while China boasts of having used the technology in reverse to keep the Beijing Olympic Games of 2008 dry.

Recent research, however, suggests that it’s not as effective as was previously believed.

Source: The Institute of Physics, London

For more info

To read Robert Sprenger’s article about rainmaking in the March 1948 issue of The Puget Sound Alumnus, go to bit.ly/2ak8DE6