“At the distance of rather more than a league from the city” (p.18). Mary Shelley uses the measurement “league” often throughout her novel. It is not as commonly used presently as it has been in the past. There are two different distances for a league, one for on land, and one for on water. The distance of a league on land is exactly three miles. The distance of a league on water is approximately 3.452 miles. The title of the famous book by Jules Vernes is "20,000 Leagues under the Sea". This distance is already in “water leagues” (nautical) so it is equivalent to 60,000 nautical miles.
“Measurements & Units.” Final Answers. 30 Aug. 2009. http://home.att.net/~numericana/answer/units.htm#league