Details of Bern's Zytglogge — the medieval clock tower whose astrolabe dial and hour-striking automata still perform today — set down on paper in 1534, when the clock itself was already a century old. These are working drawings from the drawn-by-hand era of horological record: the tower studied the way one studies a machine one may someday have to repair. Almost five centuries later the clock still runs, which makes this one of the oldest condition reports in the house.

Maker: Unknown draughtsman
Date: 1534
Medium of the original: Plate
Original held by: via Wikimedia Commons
Credit: via Wikimedia Commons · via Wikimedia Commons
Rights: Public domain, verified
Catalogue number: PA-00541

As chosen: 12 x 8 in, art print, classic frame
Picture	12 x 8 in
Outside size	13.6 x 9.6 in
Depth	0.9 in (22 mm)
Weight	[[REAL PROOF NEEDED: shipped weight per size and frame]]
Hanging	[[REAL PROOF NEEDED: hanging hardware Prodigi fits to this frame]]
Material	Enhanced matte art paper, 200 gsm; acrylic glazing
Made in	Charlotte, North Carolina, by Prodigi

Before a size goes on sale, the file is measured against it: pixels per inch at that size, how much of the picture a crop would lose, tone and sharpness. A size that fails is not offered, so there is nothing to choose wrong.

How the print check works

Sizes offered
Size	dpi	Grade	How it fits
12 x 8 in	182	Good	Trimmed 0.3%

Sizes withheld
Size	Why
10 x 8 in	Wrong shape: a 16% crop
14 x 11 in	Wrong shape: a 15% crop
16 x 12 in	Wrong shape: a 11% crop
18 x 12 in	121 dpi; a historical scan is never enlarged
20 x 16 in	Wrong shape: a 16% crop
24 x 16 in	91 dpi; a historical scan is never enlarged
24 x 18 in	Wrong shape: a 11% crop
30 x 20 in	73 dpi; a historical scan is never enlarged
30 x 24 in	Wrong shape: a 16% crop
36 x 24 in	60 dpi; a historical scan is never enlarged
40 x 30 in	Wrong shape: a 11% crop
48 x 36 in	Wrong shape: a 11% crop
60 x 40 in	36 dpi; a historical scan is never enlarged