Translating the Phrase from 20th to the 18th century [closed]

Needing to write a novel that is set in the 1800's finding the correct phrases and words used back then is challenging. I just want to know where I can find the correct phrases and words for the novel. Is there a website that can help or a 1800 dictionary.

Various dictionaries from 1800 or thereabout are available online. For British English, H.J. Todd's four-volume revision of Samuel Johnson's A Dictionary of the English Language (with full citations) from 1818 is probably the most detailed:

Volume 1 (A–C)

Volume 2 (D–H)

Volume 3 (I–Q)

Volume 4 (R–Z)

A two-volume English dictionary from the same general period is Thomas Sheridan, A Complete Dictionary of the English Language, revised edition (1797):

Volume 1 (A–H)

Volume 2 (I–Z)

A single-volume option is Stephen Jones, Sheridan Improved: A General Pronouncing a Explanatory Dictionary of the English Language, third edition (1798).

For U.S. English (largely cribbed from Johnson and other British English sources), the first large-scale source is Noah Webster, An American Dictionary of the English Language (1828), available through Google Books in a two-volume set:

Volume 1 (A–I)

Volume 2 (J–Z)