Jonathan Swift Quote:

Jonathan Swift formulated "A proposal for correcting, improving and ascertaining the English tongue" (1712): an Academy would 'fix language forever'

Standardisation in the 18th Century

1712: Jonathan Swift writes to the Lord Treasurer urging the formation of an English Academy to regulate usage as many "gross improprieties" could be found in "even the best authors."

1721: Nathan Bailey produces the first substantial Etymological English Dictionary. Criticised for being vague about usage of words and a lack of support. 

1755: Dr. Johnson's dictionary. The first comprehensive dictionary. However, Johnson saw the limitations as he mocks the lexicographer who imagines that his dictionary "can embalm his language" as "to enchain syllables, and to lash the wind, are equally the undertakings of pride."

1762: Robert Lowth's short introduction to English Grammar. Some say he established the prescriptive tradition. Rules such as: don't split the infinitive, don't use a preposition at the end of a sentence and don't use double or multiple negatives.

1770: Thomas Sheridan moved to Bath and founded an Academy for the regular instruction of young gentlemen in the art of reading and reciting and grammatical knowledge of the English tongue. He saw the dialect variations from 'standard English' as 'vulgar' and 'provincial'.

1785: Thomas Dyche's bestselling A guide to the English Tongue. He wrote a bit about the long s. This could possibly be standardisation as it establishes 'ways' to speak correctly.

1794: Lindley Murray's published English Grammar. "was without doubt the most popular and frequently reprinted grammar of English during the nineteenth century"

Many of these acts of standardisation were by educated and upper-class people leading to prejudice against other dialects i.e. Sheridan's opinion of variations of standard English. 

Bibliography:
http://users.ox.ac.uk/~cram/iss30/wischer.htm#fn1
http://www.acsu.buffalo.edu/~duchan/new_history/enlightenment/sheridan.html
http://www.universalteacher.org.uk/lang/languagechange.htm