Should you locate a scanned copy of the 1935 Breviarium Carmelitanum (Latin only), here is how to use it:
The Second Vatican Council (1962–1965) called for a revision of all religious orders' breviaries to align with the Liturgia Horarum (Liturgy of the Hours). After 1965, the modern Carmelite Order (both the Ancient Observance—OCarm—and the Discalced Carmelites—OCD) adopted the standard Roman Liturgy of the Hours, albeit with proper propers (specific readings and antiphons) for Carmelite feasts.
Consequently, a "historical" or "pre-Vatican II" Carmelite Breviary is today a rare Latin-English diglot or Latin-only book. The phrase Carmelite Breviary PDF typically refers to one of three things:
The foundational document of Carmelite life is the Rule of St. Albert, given to the hermits by the Patriarch of Jerusalem between 1206 and 1214. While not a breviary in itself, the Rule mandated the recitation of the Divine Office. It prescribed that the hermits should "keep vigil" (night prayer) and recite the canonical hours. This established the rhythm of prayer that necessitated the development of a specific liturgical book.