I purchased the flute on EBAY and although it is physically good it does not seem to be on key, even with the slide almost fully out. Does anyone have experience with this flute? 
Is it in tune with itself but not getting to ānormalā pitch? Many older were tuned to a higher or lower pitch than our current concert pitch (based around an A being 440hz), you may have bought one of those.
If itās not in tune with itself, there might be a problem with the cork, which is not immediately visible but is very important to tuning.
I have to pull the slide way out and then not all notes are where they should be. Frustrating. I hope I can get my money back. Maybe someone who knows how to fix flute would love it. It is a beautiful flute with nice tone butā¦..
The company Riviere & Hawkes were in production from around 1876 - 1889, which was a period when tuning was set at a higher pitch. Anything from around 447 - 455 Hz. The chances are that your flute may be one of these.
Hello Russell, It would probably be a good idea for you to post a clear full photo of the flute with the slide extended to the position where you are playing closest to 440 Hz., in order to allow members here give you the best advice 
I really appreciate the response. Can you please tell this old guy how to upload pictures to this site? Gosh I still use Morse code.
Iām afraid I canāt help you out in that department ( still using a drum myself 
) but Iām sure there are plenty of qualified members reading this thread who will be only too happy to guide you through the process. One thing to bear in mind is that even on instruments that are closer to, and will play in Concert Pitch A = 440 Hz., the intonation leaves a bit to be desired. Quite often the A and B will play sharp. G usually behaves itself, F# flattened, E a little sharp, and invariably the bottom D flattened. Over time, with practice, this can be ameliorated with playing technique and eventually you develop the skill to play the instrument more " in tune " with itself, but donāt expect perfection. There is a lot more to these instruments than meets the eye, and they are more challenging to play than their modern counterparts, but if you persevere the rewards are there. 
I will host the images. Sent a pm with my emailā¦
Nice one Patrick
Pending images, can you also measure and tell us the sounding length in mm? - Centre of embouchure to level with foot end, measured on assembled flute, all parts pushed fully together.
FWIW I have handled a couple of RiviĆØre & Hawkes flutes and they are by no means necessarily High Pitch instruments.
Unless the vendor specifically stated the instrument was playable at modern Concert Pitch, you have no grounds for requesting return/refund if it isnāt!
Hello:
I will measure after work. The vendor stated 440 Hz. It is in beautiful like new shape but my other flutes are dead on but this is not. The intonation is on the mark on some notes but way off on others. It is beautiful to look at but ā¦ā¦.
Could a mis-positioned headjoint cork be responsible for erratic tuning (esp. if across the octaves)?
V
EDIT: I see this was already suggested by bigsciota, sorry, I should just say DITTO
Is here a way to āmeasureā the placement of the cork in the head? If so how and what should it be. The flute is physically beautiful and I would like it to work.
Cork positioning post:
https://forums.chiffandfipple.com/t/having-trouble-with-my-embouchure/57191/7
I have to pull the slide way out and then not all notes are where they should be. Frustrating. I hope I can get my money back. Maybe someone who knows how to fix flute would love it. It is a beautiful flute with nice tone butā¦..
Could you tell us which notes are not where you expect them to be, and by how far they are sharp or flat? This may shed light on the problem, and allow people to comment in more detail.
Frankly, any misplacement of the stopper is not going to cause the gross discrepancies being described. Of course it needs to be set right, but doing so will not cure severe scaling issues.
Sounding length?
I suppose until the procurement of the further required evidence, all is speculative up to this point, including the notion that the flute might even play in Eb. Nothing like a bit of mystery to get the imagination going. From Russellās visual descriptions, it may well be worth the wait.