Let's say an 18th century historian came across an account of Greek humanoid automata, or Chinese flying wooden birds - would he think of these things as having actually existed? Or would he assume they were mythical?
Also, I'd be really interested to know how these views would change over time: Would a medieval scholar have believed the accounts? Would a late 19th century history professor have scoffed at the idea that ancient civilizations could have built anything so advanced? And finally how do we in the present separate out the fact from the fiction, given that we know, more or less, which things would be technologically plausible?
Oh boy! A chance to pull out one of my cooler sources! In the 1712 encyclopedia of science called The Universal Library Or, Compleat Summary of Science, the authors give a list (in the "geometry" section) on "Artificial Rarities". Here are some examples. They're presented without comment by the author, so it's not clear to what extent he believed the stories. He notably reports on a few Antikythera-type devices.
Simon Stevinus made Prince Maurice a Flying or Sailing Chariot, which in Two Hours Time would pass with Twenty Eight Persons from Scheveling to Putten (Towns in Holland) which is about Forty Two English Miles.
Sapor King of Persia [Shapur, ~250 AD] had another Glass, wherein he sat like Jupiter and saw the Sun, Moon and Stars, &c. Rise and Set around him, and changing and keeping its Course continually, the Moon being every Month New and Full as in the Heavens.
Johannes Regiemontanus made that famous wooden Eagle (which by reason of Weights equally poised within the Body, and a certain Proportion of Air as the Spirit of Life inclosed) mounted up on high and flew to meet the Emperor Maximilian at Nuremberg, which meeting him in a Flight of half a Mile, turn'd back of its own accord and flew Home before him. He also made the Iron Fly that flew about a Table.
Greniborgus made an Image of Plaister [plaster], which with infusing a Voice into it, as the distances of Breath would permit, he then stop'd up, and after divers Windings and Turnings came to the Head and Face of the Statue, and for as much as the force of the Words were sharp, and there was a succession of Spirits, they did expedietly move the Jaws and Tongue (made moveable for that purpose) and it dexterously uttered variety of Syllables.
In the Reign of our King Richard II. A. D. 1387, a Head of Earth was made at Oxford, that at a Time appointed spoke these Words, Caput dedecetur, The Head shall be cut off : Caput elevabitur, The Head shall be lifted up : Tedes elevabuntur super Caput, The Feet shall be lifted up above the Head.
Pythagoras (we read) could write what he pleased on a Glass, and by the Reflexion of the same Species*, would make those Letters appear on the Circle of the Moon so plain as to be read by any Person some Miles distant from him. Agrippa affirms it possible, and not unknown to himself and others...
Some of the authors' other examples include tiny carvings of animals or other scenes that would fit into a nut, a peppercorn, or other miniscule spaces, a map made of expertly carved gemstones, and a lamp in a tomb that had been burning for 1200 years.
Others can comment on this better than I can, but I suspect that by 1850, you'd find considerably more skepticism than in 1712.