I have also two small aquarells signed "P.Roschankowsky".
With Finnish Google, can be found this painting from Helsinki City collections
But sadly there is only information about house, not from the artist.
http://www.hel2.fi/kaumuseo/kehyksis...haniemi_1.html
An here's a scanned Finnish postcart also picture of orginal Roschankowsky painting.
http://www.postcrossing.com/postcards/FI-827100
Finland Quality Auction Hagelstam has been sold some years ago one of his paintings with 1200euros.
In all of these sources his firstname is mentioned to be Paul.
I would much apreciate ALL information about him. Years of living, history etc..
It's funny theres no information to be founded about him from Finland, but he has been painting very good quality aquarells from Helsinki sights.