In the opening pages of his 1845 manual on the daguerreotype, J. H. Croucher slips in a small but startling aside about what the field of photography is actually called:

"Notwithstanding the many valuable discoveries with which the researches of Sir John Herschell, Mr. Fox Talbot, Mr. Robert Hunt, and other distinguished philosophers, native and foreign, have recently enriched the science of Photography, or, as it is now termed, Actino-Chemistry, the Daguerreotype process, first divulged in 1839, still retains the highest place in public estimation."

"As it is now termed, Actino-Chemistry." In 1845, six years after Louis Daguerre unveiled his miracle to the world, there was a serious push to rename the entire field. The word "photography" — light-writing, from the Greek phos and graphein — was considered by some philosophers to be too superficial. It described only the visible product. The new proposed name, actino-chemistry, from the Greek aktis (ray) plus chemistry, described what was actually happening: chemical reactions driven by radiation.

The book itself was published in London by Willats, opticians of Cheapside, as the second installment in their "Photographic Manuals" series. Croucher wrote for the burgeoning crowd of amateurs who had bought daguerreotype kits and were now exposed, as he gently puts it, "to frequent annoyance and disappointment." His goal was practical: short directions, no technicalities.

So why did "actino-chemistry" lose? Partly because Herschel's coinage "photography" was simply easier to say, and the public had already adopted it. But the deeper reason is that the term was too accurate. It correctly identified that photography was a subset of a much larger chemical phenomenon — light driving reactions — and the public didn't want a subset; they wanted a name for the magical thing that produced portraits.

But the root never quite died:

• Actinic light — still used by photographers and printers to describe UV-rich light that triggers chemical change
• Actinometer — a real instrument used today to measure radiant flux
• Actinic keratosis — the dermatological term for sun-damaged skin
• Photochemistry — the modern academic field, which is precisely what Croucher's contemporaries meant by "actino-chemistry"

The 1845 philosophers were ahead of their time. They understood, decades before the photoelectric effect was formally described by Hertz (1887) and explained by Einstein (1905), that light was a chemical agent — not just a passive illuminator, but an active reagent that broke and made bonds. The "Practical Hints" book is, on its surface, a how-to for polishing silver plates and fuming them with iodine. But buried in its first paragraph is a glimpse of a road not taken: a parallel universe where every smartphone has a tiny actinochemical sensor, and where "actinographer" would be the name for someone who takes pictures.