Both Uses

oblige
in
The Adventure of the Speckled Band
(Edited)

To determine its exact meaning I have been obliged to work out the present prices of the investments with which it is concerned.
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obliged = required
I should be very much obliged if you would slip your revolver into your pocket.
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obliged = grateful or indebted

Definitions:

(1) (oblige as in: I am obliged by law.)
require (obligate) to do something
(2) (oblige as in: I obliged her every request.)
grant a favor to someone
(3) (obliged as in: I'm much obliged for your kindness)
grateful or indebted
(4) (meaning too rare to warrant focus)
Much more rarely, in classic literature you may see oblige as a synonym for ask as when Jules Verne wrote "I obliged the Professor to move his lamp over the walls of the gallery," in Journey to the Center of the Earth.