In 1856, a young man named W. Sparling published a photography manual with a curious credential on the title page: "Assistant to Mr. Fenton, Honorary Secretary to the Photographic Society." That "Mr. Fenton" was Roger Fenton, the man now credited as the first war photographer, whose famous images of the Crimean War (1855) invented photojournalism. Sparling had been there with him — hauling chemicals across a battlefield inside a converted wine merchant's van.

So when Sparling opens his manual with an introduction imagining what photography might become, he isn't speculating from an armchair. He's writing from experience nobody else in the world yet possessed:

Whether employed as an assistant to the artist, or a means of sending home from far-off scenes of war and death the portrait of a friend, or the spot whereon, perhaps, he died or conquered, what can equal its truthfulness? what can surpass its beauty? By the aid of the sunbeam the physician may now delineate the gradual changes produced by disease, with a faithfulness hitherto unknown; the architect can obtain the most elaborate details of a building in a few seconds.

Read that list again. In a single paragraph, in 1856, Sparling names:

• War photography — including the specific modern impulse of bringing home images of the dead and the ground they fell on. This anticipates every Vietnam magazine spread, every embedded photojournalist, every viral image from Ukraine.
• Medical imaging — using photography to track "gradual changes produced by disease." He is describing longitudinal clinical photography as a diagnostic tool. Dermatology photo atlases and progression tracking wouldn't become routine for decades. X-rays were forty years away.
• Architectural surveying — obtaining "the most elaborate details of a building in a few seconds." This is photogrammetry, the technique now used by everything from Google Earth to construction lidar.

He even hints at a fourth application in a note tucked under his title: "PHOTOGRAPHED UPON THE WOOD WITHOUT PENCILLING." This refers to a nearly-forgotten technique where a photograph was projected or printed directly onto a woodblock so an engraver could cut through it — skipping the artist's pencil draft entirely. It was the mid-Victorian version of "print to PDF, then to CNC." The technique flourished briefly, then vanished when halftone printing arrived in the 1880s and made the whole workflow obsolete.

What's striking is Sparling's confidence. He calls photography "the most important application of chemical philosophy… which modern science has discovered" — while admitting "the science is at present in its infancy." He couldn't have known about digital sensors, MRI, satellites, or Instagram. But he understood, viscerally, that a machine which produced truthful pictures cheaply and quickly would eat every field that depended on visual evidence. Doctors, soldiers, builders, artists. He was right about all of them.