A 20th Century gimbaled Ship Captain's barometer by J.J.B.L.M. 16 a 22 R. N. Desterro Lisbon. 223047.

This is a lovely example of a barometer designed for use in a marine setting. The barometer is designed to be portable and to split its use at home and on board a sailing ship. Ship captains usually owned barometers like these. They would bring them with them when they set out to sea. The instrument's purpose was to forecast the coming weather. As a result, it was a helpful tool. The brass gimbal is designed to be rigidly secured to the wall or the bulkhead of a boat. This way, when an owner of such an instrument brought theirs on board, they would have a place to secure it. The gimbaled mounting system was designed to maintain the instrument vertically regardless of the roll, pitch, and yawl of the boat sailing over the waves. The arm extends the barometer out from the wall so it can move freely. When not at sea, the barometer was designed to hang from the loop or ring at the top of the case.

This example features a brass cylindrical case. The long middle section is wrapped in black leather. The glass barometer tube is enclosed in the length of the case. A brass knob is located on the right side, just below the mounting point for the gimbal. This knob controls the vernier situated in the upper section behind the glass. One would use this each time they viewed the instrument.

The instrument display is behind the curved piece of glass in the upper section. The engraved plates are brass and have been treated with a silver wash. The faceplate on the right is engraved with incremental scales ranging from 26 to 31 inches. It is this scale that the mercury level in the main tube is read against. The changes in the level of mercury will forecast the weather. This is the purpose of this device. The faceplate on the left is engraved with the appropriate forecasts for the mercury level. These include "Stormy / Mch Rain / RAIN / Change / FAIR / Set Fair and Very Dry." The maker's name is engraved below. This reads, "J.J.B.L.M. / 16 a 22 / R. N. Desterro / Lisbon."

 
The wall-hanging instrument measures approximately 37 inches long and protrudes from the wall 10.5 inches mounted on the current gimbal. 

Inventory number 223047.