Who was one of the first composers to use clear rhythmic notation?

Franco de Cologne

Explanation:

   The development of musical notation occurred initially through vocal music, and the means of transmission of the songs was exclusively oral. As you can imagine, this method was not very efficient, and in transmitting from individual to individual much was lost. The importance of religiosity among peoples in this process cannot be denied. For example, the emergence of Christianity, which led to the practice of gathering among the faithful and the collective worship through songs, thus making it necessary for something to help the memory of the singers. At first, in the Christian Church, it was sung only in unison, but with the addition of secondary voices, the importance of representing what was sung was imminent. This was the case throughout the history of music: as the complexity of the works increased, so did the need to improve notation systems. It can be said that all theoretical and practical knowledge of counterpoint, harmony and rhythm has gone hand in hand with the development of musical notation until we reach what we know today.

    The richest description of measurable notation is found in Fanco de Cologne's treatise Ars cantus mensurabilis (The Art of Measurable Music), named after the notation he described. The virgin represented the long, which could be perfect (three tempora), or imperfect (two tempora). The punctum represented the brev, which could be normal of one tempus (brevis recta) or altered of two tempora (brevis alter).

where and what are the statements?