Were fourth rates like later second-class battleships?

Was a fourth rate comparable to an 1890s second-class battleship?

Probably, as a rough comparison of relative fleet roles. Third rates were the principal ships of the line, so it is not an exact equivalence across periods.

A comparison with an 1890s second-class battleship receives qualified agreement. Third rates are described as the main body of ships of the line and a useful balance of capability. Fourth rates can therefore be considered in relation to a larger navy's more powerful principal fighting ships. This is an analogy about relative fleet position, without a claim that ships from the two eras had matching capabilities.