Nice find.
A star finder and identifier is “Used in conjunction with an almanac to identify the stars and plot the position of planets.”
From:
https://collection.sciencemuseumgrou...nal-instrument
And:
“British Admiralty Star Finder and Identifier (NP323) is used to predict the bearing from true north (azimuth) and angle above the horizon (altitude) of the brightest stars. It is used for setting up star sights so that observations can be made using a firm horizon, by pre-setting the sextant and looking over the compass. In this way stars can be observed through the telescope before they are easily visible to the naked eye.
Star sights using this technique are much more accurate than if taken when the sky is dark enough to recognise the stars in constellations with the naked eye, due to the superior quality of the horizon. The instructions provided with the identifier are explicit.
Planets can also be pre-set using the identifier, enabling daylight sights of Venus and occasionally Mars and Jupiter.”
From here:
https://www.amnautical.com/a/s/produ...and-identifier