This is an interesting news report I found. It discusses some clever mechanical devices used to sabotage ships. The devices are secreted inside the ship, against the hull, and utilise the movement of a ship through the waves to steadily and slowly bore or cut a hole in the hull. This report from about 1876 was repeated in some other newspapers at the time, in identical reports referring to the Bremerhaven attack and provided as context for other types of attacks on ships. However, I have dug away and not found any other details of such devices. Really this single report. Intriguing. The explanations are not entirely clear, I’m afraid.
