(the arithmetician), wrote a work of which the second chapter was "On the dust figures."[[252]]
The ġobār numerals themselves were first made known to modern scholars by Silvestre de Sacy, who discovered them in an Arabic manuscript from the library of the ancient abbey of St.-Germain-des-Prés.[[253]] The system has nine characters, but no zero. A dot above a character indicates tens, two dots hundreds, and so on,
At first sight there would seem to be some reason for believing that this feature of the ġobār system was of
Arabic origin, and that the present zero of these people,[[256]] the dot, was derived from it. It was entirely natural that the Semitic people generally should have adopted such a scheme, since their diacritical marks would suggest it, not to speak of the possible influence of the Greek accents in the Hellenic number system. When we consider, however, that the dot is found for zero in the Bakhṣālī manuscript,[[257]] and that it was used in subscript form in the Kitāb al-Fihrist[[258]] in the tenth century, and as late as the sixteenth century,[[259]] although in this case probably under Arabic influence, we are forced to believe that this form may also have been of Hindu origin.
The fact seems to be that, as already stated,[[260]] the Arabs did not immediately adopt the Hindu zero, because it resembled their 5; they used the superscript dot as serving their purposes fairly well; they may, indeed, have carried this to the west and have added it to the ġobār forms already there, just as they transmitted it to the Persians. Furthermore, the Arab and Hebrew scholars of Northern Africa in the tenth century knew these numerals as Indian forms, for a commentary on the Sēfer Yeṣīrāh by Abū Sahl ibn Tamim (probably composed at Kairwān, c. 950) speaks of "the Indian arithmetic known under the name of ġobār or dust calculation."[[261]] All this suggests that the Arabs may very
likely have known the ġobār forms before the numerals reached them again in 773.[[262]] The term "ġobār numerals" was also used without any reference to the peculiar use of dots.[[263]] In this connection it is worthy of mention that the Algerians employed two different forms of numerals in manuscripts even of the fourteenth century,[[264]] and that the Moroccans of to-day employ the European forms instead of the present Arabic.
The Indian use of subscript dots to indicate the tens, hundreds, thousands, etc., is established by a passage in the Kitāb al-Fihrist[[265]] (987 A.D.) in which the writer discusses the written language of the people of India. Notwithstanding the importance of this reference for the early history of the numerals, it has not been mentioned by previous writers on this subject. The numeral forms given are those which have usually been called Indian,[[266]] in opposition to ġobār. In this document the dots are placed below the characters, instead of being superposed as described above. The significance was the same.
In form these ġobār numerals resemble our own much more closely than the Arab numerals do. They varied more or less, but were substantially as follows: