century, but did not affect Standard English until the later 17th century. It has affected most varieties of contemporary English, which have distinct vowels in pairs such as cat, cart. In non-rhotic accents, the of cart has been lost; in modern RP the word is pronounced , distinguished from cat only by the quality and length of the vowel. This lengthening occurred when was followed by non-pre-vocalic ; it did not generally apply before intervocalic (when the was followed by another vowel). Hence the first vowel of carrot and marry has normally remained the same as that of cat (but see the mary–marry–merry merger). However, inflected forms and derivatives of words ending in (historic) generally inherit the lengthened vowel, so words like barring and starry have as do bar and star. Before fricatives Unlike lengthening before nonprevocalic , which applied universally in Standard English, lengthening, or broadening, before fricatives was inconsistent and sporadic. This seems to have first occurred in the dialects of Southern England between about 1500 and 1650. It penetrated into Standard English from these dialects around the mid-17th century. The primary environment which favored broadening was before preconsonantal or morpheme-final voiceless fricatives . The voiceless fricative has never promoted broadening in Standard English in words like ash and crash. There is, however, evidence that such broadening did occur in dialects. Once broadening affected a particular word, it tended to spread by analogy to its inflectional derivatives. For example, from pass () there was also passing . This introduced broadening into the environment _sV, from which it was otherwise excluded (compare passage which is not an inflectional form, and was never affected by broadening). In a phenomenon going back to Middle English, alternate with their voiced equivalents . For example, late Middle English path alternated with paths . When broadening applied to words such as path, it naturally extended to these derivatives: thus when broadened to , also broadened to . This introduced broadening into the environment before a voiced fricative. Broadening affected Standard English extremely inconsistently. It seems to have been favored when was adjacent to labial consonants or . It is apparent that it occurred most commonly in short words, especially monosyllables, that were common and well-established in English at the time broadening took place (c. 1500–1650). Words of 3 or more syllables were hardly ever subject to broadening. Learned words, neologisms (such as gas, first