That is a nice early Schweppes, on the higher end for value. I assume yours has a pontil mark, as Schweppes bottled on Margaret Street from around 1809-1830. Yours is much harder to find than the common Berners Oxford St. Torpedo. To accurately determine the value, we would need to see pics as I think they came in different colors which affects the value. Condition is also a factor. I have seen the darker green ones sell around $1800-$2200. HERE is an early discussion about the bottle.
Interesting history of Schweppes LINK.
Very nice, you may want to tumble it to get the hazing and wear off if you are aiming to re-sell the bottle. This may not be the best thing to though, as the embossing is a bit faint. Hopefully someone can chime in and inform us whether it would be a good idea or not. A $1000+ bottle I would still say.
Thankyou it's been in my loft for good 7 years rolling around my X was a fisherman and have various bottles jugs etc that were trawled up from the bottom of the sea didnt know they were worth anything this one used to be balenced on glass shelf in my bathroom opps have done a lot of research on it so amazing and interesting to learn of its history and value x