We have not included the addition of the aspirate among the number of errors, where it indicated only an unimportant modification of a correct sound. It had its origin in the difficulty that was found in believing that there could be more than one sign in the alphabet to express precisely the same sound. We have seen that Hincks had just shown that these signs do in fact express the same sound, and that their employment depends solely upon the vowel that follows. After Major Rawlinson’s first alphabet was in print, he arrived, independently, as we have already stated, at precisely the same conclusion. He had long been struck with the peculiarity that certain consonants are only to be found followed by a particular vowel, and in his first alphabet he indicated five letters thus distinguished. These were: 19, _t_ with _i_; 29, _m_ with _i_; 33, _m_ with _u_; 40, _r_ with _u_; 43, _n_ with _u_; and he observed especially the affinity the vowel _i_ had for certain consonants—a peculiarity he noticed also in some of the Scythic languages.[566] When once his attention was directed to these facts it was not long before he set himself to account for them. One of the most useful contributions to decipherment made by Lassen arose from the suggestion that an _a_ is understood though not always expressed after a consonant, when not followed by another vowel. Indeed until this idea occurred to him the result of decipherment was the apparition of a long series of words consisting of an agglomeration of consonants which no living tongue could pronounce. The next step to be made, resulted from the observation that some letters were always followed by _i_ and others by _u_. A laborious classification of each letter according as it was followed by each of these vowels was therefore undertaken, and the result was sufficiently remarkable. It showed that in two cases in the grade of sonants (_d_ and _m_) there was a different sign according as the letter was followed by _a_, _i_, or _u_. Conversely, there were three cases in the grade of aspirates (_th_, _y_, _sh_), where the same sign might be found before any of the three vowels; and finally there were several cases in the grade of surds (_k_, _t_, and _r_), where it was noticed that the same sign was followed by either _a_ or _i_, and that a different sign was used before _u_. Taking these facts into consideration, Rawlinson thought he observed sufficient regularity to justify him in formulating the general law that, for some unexplained reason, the grade of surds in each class were expressed by two signs, one used before _a_ and _i_, the other before _u_; the grade of aspirates by one sign only, equally available before any of the three vowels; and the grade of sonants by three signs, each applied to one vowel only. He admitted that there were numerous exceptions to the rule; indeed, the class of dentals is the only one where the series is complete, but the exceptions he was inclined to