English historical phonology aims at uncovering the systems of sounds at various stages of the language and at understanding the ways in which the different stages and regional variants are related. The first volume of Richard Hogg’s two-volume A Grammar of Old English is devoted to phonology (volume two, written with R. D. Fulk, treats morphology and is discussed later in this essay). Hogg offers a richly detailed study that adopts the regularity of sound change as a guiding principle. He summarizes much previous work and balances traditional philology with modern generative phonology, including analysis of both Germanic and of Old English dialects. Charles Jones’s A History of English Phonology provides a period-by-period discussion of sound inventories and sound change in English, treating change as an ongoing, recurrent process and stressing the unity of past changes with ongoing ones. Jones brings in many technical concepts with a minimum of theoretical overkill, discussing vowel lengthening and diphthongization in Old English, fronting and raising of vowels, Middle English open syllable lengthening, and, of course, the Great Vowel Shift, the most famous sound change in the history of English.
The Great Vowel Shift refers to the series of changes affecting long vowels from about the middle of the fourteenth century to beginning of the eighteenth. The system of long vowels reorganized itself, with low and mid vowels raising a step to become mid and high respectively, and the earlier high vowels /i/ and /u/ becoming the diphthongs /ai/ and /au/. Thus, to take just two examples, Chaucer’s Middle English Aprill had a low vowel (as in present day “app”), which became the mid vowel of present-day April (the vowel of “ape”), and Middle English hus had a high vowel (like present-day “hoot”), which became the diphthong in house (the sound in “ouch”).
Patricia Wolfe’s Linguistic Change and the Great Vowel Shift in English examines much of the data on which theories of the shift have been based, considering the relative chronology of the various steps and discussing rhyme and spelling evidence and descriptions of vowels by scholars in the sixteenth, seventeenth, and eighteenth centuries. There is still active scholarly discussion about the details of the Great Vowel Shift—whether it was a unitary process or not, a push-chain upward by the lower vowels, or a drag-chain by the high vowels. Much of that literature requires some background in phonological theory and is played out in scholarly journals. Also requiring some background are two important studies of the sound structure of early English poetry: R. D. Fulk’s A History of Old English Meter and Donka Minkova’s Alliteration and Sound Change in Early English. Fulk argues that Old English meter can be used to establish a chronology of Old English poetry and includes both a history of Old English meter and a defense of its use as a historical tool for dating poetry. Minkova surveys eight centuries of English alliterative verse and applies the analysis of poetic practice to questions of theoretical phonology.
Orthography has its own history, and Christopher Upward and George Davidson’s The History of English Spelling traces the evolution of orthography from the Roman invasion of Britain to modern times, including an assessment of various spelling reform movements and a useful glossary of terms. M. B. Parkes’s Pause and Effect: An Introduction to the History of Punctuation in the West documents and illustrates the emergence of scribal practices and printing conventions (including the punctuation of verse) and includes an excellent glossary and seventy-four plates of illustrations.
 See, for example, Roger Lass, “What, if Anything, Was the Great Vowel Shift?” in Matti Rissanen et al. eds., History of Englishes (New York: Mouton de Gruyter, 1992); Matthew Giancarlo, “The Rise and Fall of the Great Vowel Shift?: The Changing Ideological Intersections of Philology, Historical Linguistics, and Literary History,” Representations 76.1 (2001): 27-60; and A. Paul Johnston Jr., “English Vowel Shifting: One Great Vowel Shift or Two Small Vowel Shifts?” Diachronica 9.2 (1992): 189-226