His detailed analysis of peripheral phonemes threw new light on a number of vexed problems of the historical developmnet of English.

After the war, it was the syntacits problems that attracted him. For example, he showed that in regard to positiveness and negativeness the English verb is neutral, becoming positive or negative only after its incorporation in a context.
In addition to this, he paid attention to the issues of complex condensation in English in regard to the greatly reduced dynamism of the English finite verb form.

According to Vachel, language is a complex system containing a number of subsystems or levels, each of which has its own particular structure.

Finaly, he emphasize that the written form of language is in no way only a mere appendage of spoken language, because it has its specific functions and means of expression.