Drummond's Law (named after the fictional linguist Colin Drummond) is a sound change in the western group of Hesperic. In West Hesperic, consonants followed by Proto-Hesperic *x were velarized, with the *x itself disappearing. Stops became velar stops, preserving their laryngeal features (e.g., *t'x > *k'); *sx became *h, and *nx became the velar nasal *ng. The reflexes of liquids under Drummond's Law vary by branch:
- In Albic, they became *ɣ and later *g.
- In Alpianic, they became sounds transcribed *ĺ (probably [ɫ]) and *ŕ (probably [ʀ]).
- Other West Hesperic languages: to be determined.
The semivowels apparently did not change.
In Viddan, a similar change occured, but there the affected consonants were uvularized rather than velarized, leading to the rise of a uvular series in that language. The East Hesperic languages (Valdiska and Duniscian) instead show gemination of consonants followed by *x except in initial position where the consonant does not change.