Correct usage of u & v
Initially U & V were different ways of writing the same letter. The brief and unscientific survey I have appended below seems to indicate that they were not distinguished as separate letters until the 17th century. Currently there seems to be no general consensus as to whether to exclusively use u, or distinguish between u and v.
Examples of correct usage using uvidus:
Ancient
u for all minuscule u & v.
uuidus
V for all majuscule U & V
VVIDVS
Mediaeval
u for all minuscule u & v.
uuidus
v for initial u & v, u in the middle of a word
vuidus
U or V for all majuscule
VVIDVS or
UUIDUS
Early Modern & Modern
u for all minuscule u & v, U or V for majuscules
uuidus and
UUIDUS or
VVIDVS
distinguishing u & v in minuscules & majuscules
uvidus and
UVIDUS
Examples of incorrect usage:
v for minuscule u.
vvidvs
U for majuscule V and V for majuscule U
VUIDVS
U&V in various historical texts throughout the ages
1st & 2nd Century
Roman cursive u for u & v. V in
capitals.
Various Roman Inscriptions V for U & V
4th & 5th Century
Roman Square Capitals V for U & V
Roman Rustic V for U & V
Roman Rustic U for U & V
6th Century
Uncial u for u & v. Rustic capitals. V for U.
7th Century
Uncial u for u & v
8th Century
Insular minuscule. U for V. u for u & v
french minuscule u for u & v
Merovingian uncial u for u & v
Luxeuil minuscule. U. u for u & v
9th Century
Insular majuscule. V. u for u & v
Insular hybrid majuscule. U. u for u & v
Carolingian minuscule. U for U & V. u for u & v
10th Century
Carolingian minuscule & Rustic Capitals. V for U. u for u & v
Carolingian minuscule & Rustic Capitals. U for U & V. u for u & v
11th Century
Lombardic Captials and Carolingian minuscule. U used for both U & V. u for u & v
12th Century
Protogothic. U & V both used for the same sound. u used for u & v.
The Winchester Bible uses V for capitals and u for minuscule letters, however it has U for illuminated capitals.
13th Century
Gothic u for u & v
Gothic V. u for u & v.
14th Century
Gothic V used for U. u used for u & v. Note both v & j being used in numerals eg vij
Gothic v at beginnings of words, u in the middle.
Gothic Textura Quadrata U for V. u for u & v.
Gothic Textura Sine Pedibus u for u & v.
15th Century
Rotunda Note U in the initial of Virgam. u used for u & v in text.
Renaissance Capitals and Humanist Minuscule. V used for U & V. u used for u & v
Batarde U for U & V. v and u used as initial letters, u in body of words.
The lack of distinction between u & v was not confined to Latin
Gothic cursive (with anglicana letter forms) in English.
Another gothic hand in English using v for initials and u in the middle of the words.
Batarde in French using v for initials and u in the middle of the words.
14th C German U used for illuminated capital V, V for U & V, v for u & v in initial position, u & v distinguished by sound in middle of words.
16th Century
Humanist Minuscule v at beginning of words. u for u & v in middle of words.
Gothic cursive u for u & v
Gothic cursive V for U. v at beginning of words. u for u & v in middle of words.
Batarde v at beginning of words. u for u & v in middle of words.
Printed Book. V for U & V. u for u & v.
17th Century
Humanist cursive Distinguishes between u & v by sound.
Manuscript v at beginning of words. u & v in middle of words.
Printed book. V for U & V. u for u & v.
Late 17thC Dictionary. Distinguishes between the U & V sounds both in capitals and minuscule letters.
18th Century
Printed book. Distinguishes between the U & V sounds both in capitals and minuscule letters.
Printed book V for U & V. v for initial letter and u in middle of words.
19th Century
Printed book. Distinguishes between the U & V sounds both in capitals and minuscule letters.
20th Century
Book u & v distinguished by sound
Oxford Latin Dictionary u used for u & v
Sallust in Oxford Classical Texts u used for u & v
21th Century
Vergil u & v distinguished by sound
Sallust from American Philological Association u and v distinguished by sound
Ars Amatoria Cambridge Classical Texts V for U & V. u for u & v.