In "Against Idleness and Mischief"(1715) ("How doth the little busy bee"), Isaac Watts rhymes "wax" and "makes".
Were these two words pronounced the same at the time (cf. Pope's rhyming of "obey" and "tea" in "The Rape of the Lock", where we know "tea" was pronounced "tay")? If so, which has retained its original pronounciation? Or was Watts merely using poetic licence?
I think it is most likely a partial rhyme; the vowel sounds may have been somewhat closer than they are today, but not identical, and probably not even nearly identical. Watts seems to have been working in a poetic tradition where vowel sounds did not have to match perfectly to be used as rhymes. (Systems of 'imperfect' rhyme are well exemplified in modern English song lyrics of various genres, although of course the details differ). It is possible that in some cases not only the sound, but either the etymological kinship of certain vowel sounds or their similar spelling ("eye rhyme") made them more amenable than any random pair of vowels to be used as rhymes.
I wrote an answer to a related question about Pope: Pronunciation of "lost"
In Middle English, before the "Great Vowel Shift", the difference between the vowel of wax and the vowel of make was solely one of length.
The Great Vowel shift caused both vowels to assume a more "close" or "raised" pronunciation (with a more raised tongue, which makes the mouth less open); the long vowel in make ended up becoming a more close/raised vowel than the short one in wax.
Per the timeline at Wikipedia, around 1715 the vowel in makes might have been something like [ɛː] or [eː]*, vs. [æ] in wax. While not incredibly close, these are somewhat similar: both are unrounded front vowels, and unlike the usual modern [ei̯], neither is a diphthong. Perhaps more importantly, the spelling and the example of the usage of prior poets for which the pair may have been simply [æː] and [æː] (such as, perhaps, Shakespeare) may have caused Watts to consider these vowel sounds close enough to make for an allowable rhyme.
The Oxford English dictionary does record pronunciations of make with a shortened vowel /æ/, saying
The α forms with a short a must have arisen in Middle English before the great vowel shift. J. Wright, Eng. Dial. Gram. (1905) records such forms from the northern counties and as far south as Shropshire, Staffordshire, Warwickshire, Leicestershire, and Lincolnshire; in Scots, the pronunciation /mak/ is general.
Isaac Watts was born in Southampton, Hampshire; I am not sure if this is too far south for /maks/ to be a plausible pronunciation in his mouth.
The OED also records forms of make with short /e/~/ɛ/, but I don't think that is particularly more likely than a long [ɛː] or [eː] to have been the pronunciation Watts had in mind.
I assume that "bee" in the first line and "day" in the third constituted a partial rhyme for Watts (the original vowel of bee is different from that of tea). If I'm correct, this would provide evidence that he made use of the license of rhyming on non-identical vowels.
His hymns also provide pairs such as the following, unlikely to all be full rhymes:
"done" and "unknown" ("Alas, and did my Savior bleed")
"blushing face" and "thankfulness" ("Alas, and did my Savior bleed")
"owe" and "do" ("Alas, and did my Savior bleed")
"word" and "Lord" ("Jesus Shall Reign")
"made" and "head" ("Jesus Shall Reign")
"tongue" and "song" ("Jesus Shall Reign")
"power" and "more" ("Jesus Shall Reign")
"stood" and "God" ("Our God, Our Help in Ages Past")
"place" and "less" ("Marching to Zion")
"rise" and "bliss" ("Marching to Zion")
"grace" and "righteousness" ("Joy to the World")
*That is, with a lengthened version of roughly the sound of the vowel used in the word DRESS. Although the English TRAP and DRESS vowels don't necessarily sound particularly similar to native English speakers today, Germans and Russians among others notoriously have tended to have difficulty hearing a difference between the English TRAP and DRESS vowels. Furthermore, many modern accents use a lower or less fronted value for TRAP vowel than was previously common; although often still transcribed "/æ/", the TRAP vowel in modern standard Southern British English is, per Geoff Lindsay, more accurately transcribed as [a].
Isaac Watts rhymes "wax" and "makes".
This is probably a half-rhyme: the vowel sound differs slightly but the consonants are the same.
From Old English to the 1600s, the word "wax" has been spelled wæx, wex, weax, 1800s dialect wex, wexe/vexe, waxe, waxche, vax, whax, walx, valx, waux, waks.
All of these will be phonetic spellings influenced by dialect and the teacher's dialect and pronunciation.
By the 18th century spelling had become more standardised regardless of dialect pronunciation. For example "wex" and "meks" would be good dialect pronunciations of wax and makes - and they would be full rhymes.
Watts was born and brought up in Southampton. It is quite conceivable that, to him, they were full rhymes.
As far as "tea"/"tay" is concerned, "tay" exists as a dialect form of "tea" in the UK today. This was the case in the 17th century as we can see in
1655 Chá is a leafe of a tree, about the bignesse of Mirtle; [margin] its called also Tay. translation of A. Semedo, Hist. China i. iii. 19
There is nothing amazing here. It is safe to say that, in the UK, prior to, say, 1940, there were hundreds of dialects, some unintelligible to outsiders. Over the past 75-80 years the language has levelled remarkably.
Relying on rhymes is only valid pre-18th century (and then not always) and if you know one of the words. Even then it may indicate only how the author said it or he wanted it to be read.
