"An Investigation of the Rotation Period of the Sun by Spectroscopic Methods" presents a detailed scientific study conducted in the early 20th century. The work delves into the methods used to determine the sun's rotation period through spectroscopic analysis, offering insights into the techniques and challenges faced by astronomers of the time. This historical scientific document showcases the application of early spectroscopic methods to understand solar dynamics and contributes to the broader understanding of astrophysics. A valuable resource for historians of science, astronomy enthusiasts, and anyone interested in the evolution of our understanding of the sun.