NavList:

I purchased an identical Barker box sextant new about 20 years ago in Vienna.  I have used it extensively in yachts, ships and light aircraft.  It originally had shades completely coloured, but the factory replaced them with half coloured, free of charge.

I last used it in a light aircraft a week ago when amazingly there was no hurricane, or fog, and the airstrip wasn't flooded.

I have the following additional comments.  It of course requires 2 hands to use, and the eye must be very close to the lens to read the vernier. It is most difficult to "bring the star down" or invert the sextant to bring the horizon up, so it is best to pre-set it. It is still quite difficult to pre- set the limb with the 2 speed knob; this makes doing something else at the same time, eg flying solo, tricky.The shades can be set to cover the reflected image, both images, or neither, but this can only be done whilst sighting through the peephole.  The extra eyepiece is shaded, but it is not necessary, even for artificial horizon sun shots, as both built- in shades can cover both sight paths. Reading to only 1' is adequate for deep sea or aircraft use.

The body of the sextant could have housed a small telescope stored in the spare peep hole cavity, but mine has not got this.  If a telescope were fitted to the active position, it would likely poke an eye out in rough conditions unless the user wore spectacles.  If a telescope is not stored, the body could have been made smaller, like most box sextants which unscrew the lid to function. It is the size of a large coffee mug, which gives a storage problem in a small cockpit. Wearing spectacles that cannot be removed (flying helmet) makes reading the vernier more difficult.

It does its job as a box sextant for back-packing or lifeboat use.  Because of the above, I prefer a 3/4 size conventional sextant with micrometer and rubber eyepiece low power telescope for light aircraft use, or the normal smaller unscrewing body box sextant.

Brian Walton