All 3 Uses of

dilate
in
The Hunchback of Notre Dame

At the first moment there had arisen from his poet's head, or, simply and prosaically, from his empty stomach, a mist, a vapor, so to speak, which, spreading between objects and himself, permitted him to catch a glimpse of them only in the incoherent fog of nightmare,—in those shadows of dreams which distort every outline, agglomerating objects into unwieldy groups, dilating things into chimeras, and men into phantoms.†
Chpt 1.2.6

dilating = becoming wider

These same atoms dilated in accordance with a certain law need only be condensed in accordance with another law.†
Chpt 2.7.4 *

dilated = wider than normal (bigger); or became wider

Gudule's horribly compressed heart now dilated, and she said in a low voice, as she cast a glance at her daughter, whom she had not ventured to look at while they were there, "Saved!"†
Chpt 2.11.1

Definitions:

(1) (dilate as in: dilated eyes)
become wider (bigger)
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Much more rarely, dilate can mean to add details, as to an account or idea; clarify the meaning of and discourse in a learned way, usually in writing.