More than a century before solar panels became a common sight on Indian rooftops, a little-known British bureaucrat in Bombay built a working solar steam engine—only to see his revolutionary vision crushed by the very colonial system he served. Now, a new historical analysis argues that William Adams’ forgotten story holds urgent lessons for today’s energy transition.
In an article published May 29, 2026, in The Conversation, researcher Deenesh Sohoni—author of an upcoming book on the global history of solar steam engines—rescues Adams from obscurity. Sohoni, who is working on a postdoctoral project about 19th-century solar pioneers, says Adams’ tale is one of “an inexhaustible source of wealth” ignored by shortsighted rulers.
A Clerk’s Obsession, Ignited by the Sun
Adams first became entranced by energy while working as a clerk in a London patent office in the 1860s. There, he saw early British designs for harnessing the sun. But it was French mathematician Augustin Mouchot’s 1866 solar boiler—demonstrated to Emperor Napoleon III—that truly inspired him.
“Adams would later recount his excitement at reading about Mouchot’s invention,” Sohoni writes. The young inventor patented his own rudimentary solar boiler, but quickly realised he needed a sunnier location.
When offered the post of deputy registrar of Bombay (now Mumbai) in 1873, Adams leapt at the chance. There, Sohoni notes, “he became the first Briton to design, build and test a fully-functioning solar steam engine fit for industrial purpose.”
‘The Rays Beat Like Missiles’
Adams arrived in Bombay during a cotton boom. Mills were sprouting everywhere, and firewood had been depleted for miles. The landscape, Adams lamented, had grown “bald as a billiard ball.”
Every morning before work, Adams set up an outdoor laboratory at his home in the Colaba district. He had an Indian fundhi (skilled carpenter) build tiered shelves holding 18 looking glasses, each adjustable “by the touch of the finger.”
Later experiments used 36 mirrors, making “the mercury in the thermometer boil, leaping up to over 670 degrees fahrenheit,” Adams recorded. A copper cylinder with three gallons of water boiled in exactly 20 minutes.
But his crowning achievement came in 1876. Adams built a 24-foot concave mirror and had his London solar boiler shipped to Bombay. One morning, wearing dark glasses for safety, he turned the giant mirror on a water-filled copper cylinder.
“The rays beat like missiles in a continuous and incessant storm of solar fire,” he wrote.
Within an hour, the cylinder reached 55 pounds of pressure per square inch—enough to drive a 3-horsepower steam engine. For a fortnight, Adams proudly demonstrated the device to government officials, mill owners, and local communities, even advertising public viewings in a Bombay newspaper.
‘Too Subversive’ for the Raj
In his 1878 treatise Solar Heat: A Substitute for Fuel in Tropical Countries, Adams argued that nations near the equator “possess, in their clear skies, a gratuitous and inexhaustible source of wealth, equal to that which western nations have to dig, with infinite labour and toil, from the bowels of the Earth.”
He envisioned solar-powered cotton gins and even crematoria, calling on the colonial government to invest in this substitute for costly imported coal. But his bosses were not persuaded.
The locals saw the promise. One resident wrote to Scientific American magazine, noting fuel was “scarce and dear” in his tropical district and that “there is a great opening for cheap power in small units.”
Yet Bombay’s new governor, Sir Richard Temple, dismissed solar heat as unusable “for commercial purposes on a large scale,” claiming factory owners would object to giving “the workmen a holiday on days when the sky is not clear.”
Sohoni cuts to the heart of the matter: “In truth, Adams’s invention was too subversive for Britain’s colonial officials and capitalists.” Unlike coal, solar energy was tied to seasonal rhythms—and India was also a vital market for British coal exports.
“Increasingly frustrated that neither the industrial capitalists nor the colonial government supported his vision, Adams abandoned further experiments,” Sohoni writes. “His dream of India switching away from coal to solar power, from combustion to concentration, would not happen for at least another century.”
A Century Later, a Solar Powerhouse
Today, India leads the International Solar Alliance and is the world’s third-largest solar power generator. Sohoni concludes with a pointed question: “How much further advanced would this technology be had Adams’s 19th-century solar experiments been embraced by India’s colonial rulers at the time?”
For Sohoni, Adams is more than a historical curiosity. He represents the unsung heroes of science—visionaries whose ideas were dismissed by entrenched power, only to be vindicated long after.
“The locals shared Adams’s belief in this technology,” Sohoni emphasises. But colonial conservatism, not technical failure, sealed its fate. As the world races to decarbonise, the Bombay bureaucrat’s 150-year-old solar engine stands as both a forgotten landmark and a warning.
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