These are great horns, mid 20s I think and when the Adolphe Sax name was owned by Selmer. I had one for a while (ser no 230) .They are actually more modern and better sounding horns than the Selmers of that era IMO.
You could have a look on the Vintage Saxophone Gallery website... http://www.saxpics.com/
If you want to find out about Adolph Sax; Google or Wikipedia is a good starting point.
There is an excellent museum in Brussels, with lots of originals. I'm still trying to find out the dates when they play them.
Thanks for the tips. I checked it out and found a number 11200 under the D key. This is aparently the Selmer number and dates my sax at about 1929. I used to play a lot when living in Cambridge in the 60's, but coming to Saldanha in S. Africa in 1976 I put it away as there was not much going on here. Now 40 years later I got it out of the case and it blows as good as ever.