Changes in the wave-frequencies of the lines of emission spectra of elements This book, "Changes in the wave-frequencies of the lines of emission spectra of elements", by W.J. Humphreys, is a replication of a book originally published before 1897. It has been restored by human beings, page by page, so that you may enjoy it in a form as close to the original as possible. This book was created using print-on-demand technology. Thank you for supporting classic literature.