Two registers, one machine: the clock face composed and public at the top of the sheet, and beneath it the train of wheels that makes the composure possible. The engraving's honesty is the point — a dial is a promise, and a movement is how the promise is kept. Plates like this taught the reading public what lived behind the hands, gear by labelled gear, and the Wellcome Collection's scan is fine enough that every hatched shadow in the wheelwork holds at print size.

Maker: Unknown engraver
Date: 18th–19th century
Medium of the original: Engraving
Original held by: Wellcome Collection, London
Credit: Wellcome Collection, London · via Wikimedia Commons
Rights: Public domain, verified
Catalogue number: PA-00532

As chosen: 12 x 16 in, art print, classic frame
Picture	12 x 16 in
Outside size	13.6 x 17.6 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
8 x 10 in	287	Excellent	Trimmed 5.2%
11 x 14 in	209	Excellent	Trimmed 3.5%
12 x 16 in	189	Good	Trimmed 1.1%

Sizes withheld
Size	Why
8 x 12 in	Wrong shape: a 12% crop
12 x 18 in	Wrong shape: a 12% crop
16 x 20 in	143 dpi; a historical scan is never enlarged
16 x 24 in	Wrong shape: a 12% crop
18 x 24 in	126 dpi; a historical scan is never enlarged
20 x 30 in	Wrong shape: a 12% crop
24 x 30 in	95 dpi; a historical scan is never enlarged
24 x 36 in	Wrong shape: a 12% crop
30 x 40 in	75 dpi; a historical scan is never enlarged
36 x 48 in	63 dpi; a historical scan is never enlarged
40 x 60 in	Wrong shape: a 12% crop