How has Katherine Mansfield used third person narration to reflect Miss Meadow's turmoil?

Mansfield uses a form of third-person limited narration that gets us inside of Miss Meadows's head. At the same time, the third-person perspective keeps a distance between the reader and Miss Meadows that allows us to view Miss Meadows from afar. We learn of Miss Meadows's turmoil in two mutually reinforcing ways: through her interior thoughts and through the way her mood is expressed outwardly in her environment.
The narration begins inside of Miss Meadows's consciousness as we learn of the despair that resides in her heart like a "wicked knife." This is immediately juxtaposed with an external description of Miss Meadows walking down the "cold" corridors carrying a "little baton." Because we know of Miss Meadows's despair, the cold air, an objective physical fact about the school, comes to reflect Miss Meadows's mood. Likewise, the baton she carries becomes an external manifestation of the "knife" in her heart, both objects that can hurt people.
Miss Meadows is a music teacher. As her exterior story unfolds, the reader learns of the letter she recently received from her fiancé breaking off the engagement. We therefore know that the song she picks for her students to sing, "A Lament," is an expression of her despair and turmoil. Later, a happier song expresses her joyful feelings after she receives her beloved's telegram assuring her that, after all, he still wants to wed.
Although the limited point-of-view is what one would expect in first-person narration, the third-person narration allows us to view Miss Meadows's turmoil both externally and internally.