JN-4H Jennies were advanced versions of training
aircraft used in the First World War. They were adopted
by the Post Office in the first days of airmail service.
The top speed of a Jenny was only 80 miles per hour.
The farthest a Jenny could fly without stopping was
about 175 miles. The Post Office soon retired the Jenny
from airmail service because the airplane could not meet
the demands of flying long distances and it could not
carry more than 300 pounds of mail.