One hundred years ago X-ray powder diffraction, one of the premier techniques used in the characterization of materials, was invented. Its origins can be traced to two landmark contributions presented to the scientific community in 1916. They are the better known and celebrated work carried out by Paul Scherrer under the guidance of Peter W. Debye, at the University of Göttingen, Germany, and the lesser known work of Albert W. Hull performed at the Research Laboratory of the General Electric Company, Schenectady, NY, USA. The great contributions of Scherrer and Debye have been prominently recognized. They are presented in many textbooks and in technical and scientific articles published in the area of characterization of materials using powder diffraction techniques. The camera designed by them, later called “the Debye–Scherrer camera”, was used extensively for many years and the experimental setup (“the Debye–Scherrer geometry”) is still used today. On the other hand, the work performed by Hull has not been adequately appreciated and remembered. In this communication, an account of his contributions to X-ray powder diffraction and to crystallography is presented at 100 years of his landmark publication, which appeared in the first issue of Physical Review of 1917.