Inches
Inches names 2 different subjects across the 6 encyclopedias on this shelf. Each is set out below.
Inches Millimeters. 1 0.088414 2.25583 2 0.177628 4.51166 3 0.266441
American Watchmaker and Jeweler (1892)
Millimeters. 1 0.088414 2.25583 2 0.177628 4.51166 3 0.266441 6.76749 4 0.355255 9.02332 5 0.444069 11.27915 6 0.532883 13.53497 7 0.621697 15.79080 8 0.710510 18.04663 9 0.799324 20.30246 10 0.888138 22.55829 11 0.976952 24.81412 12 1.065766 27.06995 A meter is the forty-millionth part of a meridian of the earth. A decimeter is the tenth part of a meter. A centimeter is the hundredth part of a meter. A millimeter is the thousanth part of a meter. 1 meter 10 decimeter 100 centimeters 1000 millimeters} is equivalent to {39.37079 inches, 3.28095 feet, 1.09363 yards or 0.00035138 miles 1 square centimeter = 0.15501 square inch. 1 square inch = 6.45127 square centimeter. 1 cubic centimeter = 0.06103 cubic inches. 1 cubic inch = 16.38618 cubic centimeters. To Calculate the Vibrations of a Pendulum. Multiply together the number of teeth of the wheels, starting with the one that carries the minute hand (which makes one revolution per hour), but omit the escape wheel. Multiply together the numbers of leaves of the pinions, commencing with the one that engages with the center wheel. If the first product be divided by the second, the number obtained gives the number of revolutions of the escape wheel in an hour. Multiply this figure by twice the number of teeth of the escape wheel, and the product is the number of single vibrations performed by the pendulum in one hour. The vibrations of a balance may be calculated in precisely the same manner.
Inches French Lines
American Watchmaker and Jeweler (1892)
French Lines. 1 0.0393708 0.44329 2 0.0787416 0.88659 3 0.1181124 1.32989 4 0.1574832 1.77318 5 0.1968539 2.21648 6 0.2362247 2.65978 7 0.2755955 3.10307 8 0.3149664 3.54637 9 0.3543371 3.98966 10 0.3937079 4.43296 French Lines expressed in Inches and Millimeters. French Lines. Equal to
What Has Changed in the Last Century
The 1892 table rests on two things that no longer hold. Its metre is "the forty-millionth part of a meridian of the earth" — a definition abandoned in stages, first for a platinum-iridium bar, then in 1960 for a wavelength of krypton-86 light, and since 1983 for the distance light travels in 1/299,792,458 of a second. Its conversion factor of 39.37079 inches to the metre was also superseded: in 1959 the English-speaking countries agreed that one inch is exactly 25.4 millimetres, making the metre 39.3700787 inches, so the old figures are wrong in the fourth decimal place. The French line (ligne), the watchmaker's unit of the second table at roughly 2.256 mm, has since vanished from the trade; Swiss and other movements are sized in millimetres, and the pendulum-and-balance arithmetic at the end still works exactly as described for any mechanical watch or clock.
Written for this edition, 2026.