This is Volume 1 of the Annals of the Astrophysical Observatory of the Smithsonian Institution. The book is the result of research originally due to the discovery, made in 1881 with the newly invented bolometer, of solar heat in spectral region now known as the lower infra-red spectrum. Presented in the book are tables and charts of the infra-red solar spectrum extending to 5.3 microns and mapping nearly 750 lines, of which most are below 1.1 microns and are nearly all new.