1st editions?

[RosJ]

I have a 1st edition of "The Lost World" by Arthur Conan Doyle and a 1st edition of "Captain Of the Polestar and other stories" By Arthur Conan Doyle.

Both have a few water marks and scuffed covers but "The Lost World" has all it's prints and protective paper films.

I just wondered how much they would be?

[mono]

Wow, an impressive couple of finds you have, RosJ. :nod:
Estimations on worth seem exactly what they sound like - estimations. Not only does it depend on the condition of the book (and it sounds like these have received relatively good care), but also if it has gotten re-bound in its past, and the condition of that rebinding; this practice seemed especially common in the past centuries, including when these two late 19th-century or early 20th-century books originally came out on the market. Sir Arthur Conan Doyle seems a real find, and, though written by the same man, The Lost World probably has quite a bit more monetary worth than Captain Of the Polestar and other stories amid rare book collectors, even if it appears in slighly worse condition, for the reason only of its greater popularity (weird, I know, but true); furthermore, for example, any of his Sherlock Holmes books, I have no doubt, would carry a lot more monetary worth than any of his other books - all of this gets ironically measured by the immeasurable amount of sentiment of the book buyer.
I do not know exact prices of these books, yet have a few guesses. I would highly recommend visiting at least two antiquarians, preferably in the rare book collecting area, but most antiquarians could likely give you a decent educated guess; I would not recommend going to any sort of auction agency, where countless sellers often get one of the two extremes - ripped off or highly rewarded - usually the former, but not worth the risk, I think.
Good luck! :)

[vagantes]

If you look at Abe Books you will find a first edition of The Lost World priced by a book seller at £5370. The Captain of the Polestar is priced at £300.

A good rule of thumb is to divide these prices by two.

Check your books' details against the details listed on the site to see if you do have genuine first editions.