Unriddling the Daisho-reki Calendar

Q.17th year of Tenmei (1787) Daisho-reki [Kabuki actors on fans]

There are twelve pictures of fans, each of which bears the likeness of a popular Kabuki actor of the era. How do you distinguish long from short months?

7th year of Tenmei (1787) Daisho-reki

Data

Title Creator
7th year of Tenmei (1787) Daisho-reki -
Physical data Subject (NDC)
13cm x 17cm 449.81/721.8
Note Call No.
Pasted in "Egoyomi" WA33-1

Answer