Heligoland as an ornithological observatory the result of fifty years' experience This book, "Heligoland as an ornithological observatory the result of fifty years' experience", by Heinrich Gätke, is a replication of a book originally published before 1895. 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.