E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Jonathans.
A noted coffee-house in Change Alley, described in the Tatler as the general mart of stock-jobbers.
1
What is now called the Stock Exchange was called Jonathans.
2
Yesterday the brokers and others came to a resolution that [the new building] instead of being called New Jonathans, should be called The Stock Exchange. . The brokers then collected sixpence each, and christened the house with punch.Newspaper paragraph (July 15, 1773).