In Part One, Chapter 5 (which P-V translate as "The Wise Serpent", Garnett as "The Subtle Serpent", hmm) a hitherto unknown character appears. The narrator pauses a little to describe him. Garnett translates this in past tense and here's an extract:
His words pattered out like smooth, big grains, always well chosen, and at your service.
P-V translate that sentence as:
his words spill out like big, uniform grains, always choice and always ready to be at your service. (p 180)
The change in tense is interesting. I'd guess the original is written in present tense, but Garnett felt unable to use the present historic in English: it was much less common then than now. I'd imagine there are huge amounts of translation from French where this has happened. So it's an example of a wider change in the translating language enabling a translator to be more literal.
Then the stranger speaks:
"... Only fancy, Varvara Petrovna," he pattered on, [Garnett]
"... And imagine, Varvara Petrovna," the beads spilled out of him [P-V]
It was that word "beads" that made me check the two translations. It's out of nowhere in English. You have to supply a missing metonymy: words are like grains; big grains are like beads. Again, I'm guessing, but might the word "grains" in Russian have a closer link to the Russian for "beads"? A quick look at an online dictionary suggests the words зерно and бу́син(к)а don't sound alike, but maybe they're more interchangeable culturally. Maybe Russians (in the 19th century) couldn't see a big grain without thinking of a bead.
Maybe one day this association will become part of English understanding and we won't find the transition weird, just as we don't now find the use of the present tense weird. (I doubt it, though.)
This is the kind of problem that has always put me off reading translations. I don't know if the use of "beads" is clumsy or meaningful. But the fact that P-V use the word so awkwardly strikes me as clear evidence it's a literal translation of Dostoevsky's term. Maybe Garnett's decision to repeat "pattered" is closer to Dostoevsky's original impact.
Later (p 219) the same character (Pyotr Stepanovich Verkhovensky) is described as having "words spilling out like peas", a word that Garnett also uses.