Personal size and mental sorrow have certainly no necessary proportions. A large bulky figure has as good a right to be in deep affliction as the most graceful set of limbs in the world. But, fair or not fair, there are unbecoming conjunctions, which reason will patronize in vain -- which taste cannot tolerate -- which ridicule will seize.

I cannot work out what this strange little paragraph is doing here in Ch8. Ridicule of a fat woman's sadness, though qualified as “against reason” etc, is still allowed it's place, which seems to me rather cruel. Also, the paragraph feels like an authorial aside, and sits very uneasily with the surrounding text.

The preceding paragraph is very densely written. A vivid picture is painted; we see Anne's slender form and pensive face screened by Mrs M's substantial size. We quiver with Anne's awareness of FW actually on the same sofa. We honour FW's self-command and consideration, and smile at the irony that nobody cared about Dick Musgrove when he was alive.

Then comes the paragraph in question, followed immediately by an extended general conversation about women aboard ship.

So what is the paragraph I have quoted actually for? What is it's function?

Perhaps it is meant to be humorous. Perhaps it is there as a buffer or breathing space between two important sections of the text. Perhaps JA is poking fun at stereotypes and the visual/verbal shorthand they gave rise to in contemporary literature and drama – (if you wanted to portray grief it was more effective to use a slender character than a fat one).