Sextant - Brass - Bottomley & Baird Ltd - Azimuth mirror

Here is a large antique marine/nautical navigation device for your consideration of purchase.
Not often seen on the market is one of these early brass azimuth mirrors.
The piece was made by Kevin Bottomley & Baird (KB&B) Ltd. Produced in Glasgow or London, England.
The most recent patent date shown on the raised label is 1908.
therefore, the piece probably
was manufactured within 5-7 years of that date. KB&B Ltd.
The device was originally called an azimuth mirror by Lord Kelvin when he invented the device and initially a mirror was used. When the invention was refined, the mirror was replaced by a glass prism. The instrument was designed to be placed on top of a properly made compass, to allow readings to be taken more precisely from the compass head.
The glass prism is in excellent condition. It has no chips, but a few small scratches due to use and age.
The brass instrument is in excellent condition.
There are no breaks or repairs that we can determine.
This piece fits the top of a compass