Leonard Bloomfield.

In 1933 Leonard Bloomfield publicated a comprehensive work entitled simply Language, which attempeted to lay down rigorous procedures for the description of any language.

Bloomfield cosidered that linguistics should deal objectively and systematically with observable data. Bloomfield had immense influence - far more than European linguists working during this period - and the so-called 'Bloomfield era' lasted for more than twenty years. During this time, large number of linguistics concentrated on writing descriptive grammars of unwritten languages. This involved first finding native speakers of the language concerned collecting sets of utterances from them. Second, it involved analysing the corpus of collected utterances by studying the phonological and syntactic patterns of the language concerned, as far as possible without recourse to meaning

Dicovery procedures are a set of principles which would enable a linguist to 'discover' in a foolproof way the linguistic units of an unwritten language.