Hi! Heinrich Vosberg was born in Germany in 1833, and lived until 1891. One of his paintings, Lake with sunset, Herrenhausen (1876), is even in the Royal Collection of artwork of Her Majesty Queen Elizabeth II.
http://www.royalcollection.org.uk/eGalle…
Here are some links to other paintings by him that have been auctioned in recent years and will be a guide to its current value. This would be the best place to not only get a realistic value of what your painting is worth, but also to sell it. You may contact these people who specialize in fine art to get more information about the value of the painting you have, but don't neglect the painting's collectibilty in the International market as I point out later.
Market fine art to art collectors who frequent art auctions!
http://new.artnet.com/artist/570716/hein…
http://www.askart.com/askart/v/heinrich_…
http://web.artprice.com/ps/artitems.aspx…
His work is also highly regarded in the International community, so I would urge you not to be in a hurry to sell this painting, but to throughly research all of the information I have given you above, without making any commitments to anyone regarding a possible sale, until you have the big picture of information regarding the painting you own.
http://www.internationalauctioneers.com/…
http://www.zeller.de/en/kuenstler/artist…
I do have one concern, and that is how you have spelled the name here, with a "u" instead of an "e." It would really disappointment me if you ended up just having a copy of his work.
This should help you to authenticate and sell your Heinrich Vosberg painting. Perhaps the Queen would like it—I certainly would not underestimate that idea! When complete your transaction, please remember me. I would love to hear the rest of your story!
Also, my husband has been in the fine art business, so if you need further help, do not hesitate to contact us.
Best wishes!