In the history of Ottoman Empire, the reformist movements that took place in the 19th century in the field of music have been an influential important factor in increasing theoretical studies. From the beginning of late 19th century and early 20th century, there has been a dramatic increase in the number of systematic studies such as books, booklets and articles including theoretical information about music. These works are deemed as the foundations of Turkish music. However, most of them are not included in the music literature due to their publication in Ottoman Turkish before the letter revolution. They are also important sources in terms of accessing historical information about both the authors and the studies in that period. Muallim Kazım Uz, who lived between 1873 and 1943, is one of the most important music educators of our country who is a specialist in both Turkish and Western music. In this study, his booklet titled “Musiki - Şark ve Garp Musikisinin Diyez ve Bemolleri Hakkında, which was thought to be one of the first works of Muallim Kazım Uz and published on 14 Zilkade 311 (19 May 1894) was translated into modern Turkish and examined. The examination revealed that the major subjects included definition of music, notes, pitches, half pitches, usage of sharp and bemol, maqam, major and minor concepts, scale, natural scale and sound ranges. The basic theoretical musical issues mentioned in the booklet were discussed with comparative information on the axis of Turkish and Western music, and it was evaluated as an supplementary source written for use in music education.