The definition from Google Books sourced below, indicates that nearly 100 perches equal an Arpent. I wonder why there is a difference of +80 more perches between Lucie's arpent measurements and the definition supplied by Louisiana Writers' Project?
P 685 ARPENT - a former land measure, of 100 perches, which were 22 square feet.
Louisiana: A guide to the state By Federal Writer's Project, Louisiana Writers' Project.
"French arpent land divisions are long narrow parcels of land usually found along the navigable streams of southern Louisiana, and also found along major waterways in other areas. This system of land subdivision was begun by French settlers in the 1700s, according to typical French practice at the time and was continued by both the Spanish and by the American government after the acquisition of the Louisiana Purchase. A typical French arpent land division is 2 to 4 arpents wide along the river by 40 to 60 arpents deep, while the Spanish arpent land divisions tend to be 6 to 8 arpents wide by 40 arpents deep." -- The National Atlas . Gov
Facebook Wikipedia Arpent had another answer that didn't match.
This blog post gave a wonderful illustration on a map for a Spanish Land Grant in Louisiana that was being translated from French and vice versa to Spanish.You can see that the T in Apents is missing. This only happens in Missouri.
Well, that solved only a portion of what I was looking for. There is a distinct difference in a French Arpent and a Spanish Arpent. And I already know what a perch is anyway.....It's a fish! (maybe not)
"Following the Louisiana Purchase, the U.S. government sent surveyors to Louisiana who measured existing land grants, and, calculating backward, settled on a value of 191.994 feet exactly for the arpent." -- arpent in Louisiana
So in Missouri and an Arkansas arpen is larger than a Louisiana arpent. Hmmm. It is interesting that the Louisiana Writers' Project did not actually note the differences but did indicate that an arpent was 100 perches, which is significantly less than the French apent.