We added two really interesting navigating instruments to our collection this month. Both were designed to help navigators plot a tropical storm’s circulation so the ship could navigate around the zones where the worst weather was occurring—essentially “navigating by storm.”
The first, extremely rare instrument is called a Paracyclone. It was designed by Captain François Louis Roux of the French Navy in the 1870s and constructed by A. Santi of Marseille. This particular instrument was for use in the Southern hemisphere although Santi also developed a supplemental semicircle for Northern hemisphere use. Unfortunately this piece is missing the compass plate that would help determine the course of the storm. Only two other instruments of this type are known—one is in the Science Museum in London and the other is at the Observatory of San Fernando in Madrid.