The Science of Breath presents a systematic account of pranayama, the controlled regulation of breath regarded within the yogic tradition as central to both physical vitality and mental discipline. Written for an English-speaking readership at a time when Eastern philosophical systems were first being widely introduced in the West, the work seeks to clarify the distinction between authentic yogic practice and the misconceptions often derived from superficial observation. It frames breath not merely as a physiological function, but as an organising principle underlying concentration, emotional balance, and the cultivation of will. The text proceeds through a combination of theoretical explanation and structured exercises, outlining methods intended to increase lung capacity, regulate nervous energy, and establish a more deliberate relation between mind and body. While rooted in traditional Indian concepts, the presentation reflects an early twentieth-century synthesis, translating these ideas into terms accessible to Western readers without assuming prior knowledge of Sanskrit terminology or religious doctrine. The result is a hybrid work that occupies a notable position in the history of cross-cultural philosophical transmission. This edition preserves the original text as a document of intellectual and spiritual exchange, offering insight into the reception and adaptation of yogic ideas outside their original context. It remains of interest to readers of comparative philosophy, the history of spiritual movements, and the development of modern interpretations of breath and mind.