1915 Jonah Kumalae Gold Me Soprano Ukulele Vintage - ( unusual inside markings )

Description

Vintage
1915 Jonah Kumalae Gold Me Soprano Ukulele Vintage
Belonged to my grandfather, who was an expert ukulele player and singer.
I am unsure of the date, though it has some interesting pencil marks deep inside.
Pencil mark: "15 ons" , "15 one" ,  or perhaps "15 ans"? I don't know what it means. The appraiser said this was unusual.
-Measures around 22 inches in length.
-Slight hairline crack on the back, but otherwise in great condition.
Please feel free to send an offer! (appraisal at 0-1000, though the market fluctuates)
Shipping
: It will include a brand new ukulele case, pack it in bubble wrap, and ship it in a large box. Tracking and Insurance will be included.