cable length 
In Verne's context, 600 feet 
centigrade 
 0° centigrade
 = freezing water
 37° centigrade
 = human body temperature
 100° centigrade
 = boiling water

fathom 
6 feet 
gram 
Roughly 1/28 of an ounce 
milligram 
Roughly 1/28,000 of an ounce 
kilogram (kilo) 
Roughly 2.2 pounds 
hectare 
Roughly 2.5 acres 
knot 
1.15 miles per hour 
league 
In Verne's context, 2.16 miles 
liter 
Roughly 1 quart 
meter 
Roughly 1 yard, 3 inches 
millimeter 
Roughly 1/25 of an inch 
centimeter 
Roughly 2/5 of an inch 
decimeter 
Roughly 4 inches 
kilometer 
Roughly 6/10 of a mile 
myriameter 
Roughly 6.2 miles 
ton, metric 
Roughly 2,200 pounds 