Its first engraved stamp

I just found this today, hidden in a batch of Indian papers at a local stamp fair. It is an Inland letter, postmarked 1326 [1909AD], bearing the locally engraved one abasi value adhesive. This was the first engraved issue, apparently the work of Mahmud Masi, and the first issue to bear the Western Arabic numeral [for ‘1’]. The earliest printing was imperforate. This copy shows the tell-tale marks that guide the printer in laying down the impressions to make up the plate. I don’t know what studies were ever published of this stamp. ANy one who does??

Below is the back of the cover, showing the address.