Cowgill's law[1] says that a PIE laryngeal pronounced as //h₃//, and possibly pronounced as //h₂//, turns into pronounced as //k// in Proto-Germanic when directly preceded by a sonorant and followed by pronounced as //w//. This law is named after Indo-Europeanist Warren Cowgill.
This law is still controversial, although increasingly accepted. Donald Ringe (2006) accepts it;[1] Andrew Sihler (1995) is noncommittal.[2]
Examples are fairly few:
The first two examples, however, have good alternative explanations which don't involve Cowgill's law:
If the sound law becomes generally accepted, the relative chronology of this law could have consequences for a possible reconstructed phonetic value of pronounced as //h₃//. Since Germanic pronounced as //k// results from earlier PIE pronounced as //g//, and since the change occurred before Grimm's law applied (according to Ringe), the resulting change would be actually pronounced as //h₃w// > pronounced as //gʷ//. This would have been more likely if pronounced as //h₃// was a voiced velar obstruent to begin with. If pronounced as //h₃// was a voiced labiovelar fricative as is occasionally suggested, the change would therefore have been: pronounced as //ɣʷw// > pronounced as //ɡʷ//.
. Donald Ringe. From Proto-Indo-European to Proto-Germanic. Oxford University Press . 2006 . 978-0-19-955229-0.
. Donald Ringe . From Proto-Indo-European to Proto-Germanic. Oxford University Press . 2006 . 978-0-19-955229-0.
. Andrew L. Sihler. New Comparative Grammar of Greek and Latin. Oxford University Press. 1995. 0-19-508345-8.