The vowels _i_ and _u_ have also the powers, respectively, of _y_ and _v_.
[Illustration: Partial PAGE 172] From these sounds, combined with the simple vowels, comes the Assyrian syllabarium, to which, and not to the consonants themselves, the characters were assigned.

In the first place, each consonant being capable of two combinations with each simple vowel, could give birth naturally to six simple syllables, each of which would be in the Assyrian system represented by a character.

Six characters, for instance, entirely different from one another, represented _pa, pi, pu, ap, ip, up_; six others, _ka, ki, ke, ak, ik, uk_; six others again, _ta, ti, tu, at, it, ut_.
If this rule were carried out in every case, the sixteen consonant sounds would, it is evident, produce ninety-six characters.

The actual number, however, formed in this way, is only seventy-five.

Since these are seven of the consonants which only combine with the vowels in one way.