Please note that this is a cover only.
This is an original 1916 color cover for the Illustrated World Magazine, April, 1921. This image is described in an attached one-page article (please see both images). It suggests that ships have another safeguard in the event of an emergency, in addition to wireless. Equipped with a spectrum, as illustrated, a ship could send out distress signals via beams of light.
This 90+ year old Item is rated Very Fine / Fine+. No natural defects. Light scuffing. No water damage. There are some small tears and creasing in the margin edges and general wear due to the age of the item.