Compound achromatic travelling microscope

Description

The microscope is kept in a wooden box with some green baize linings.
This travelling microscope is after a design by William Moginie, who worked for the firm of C. Baker. Coarse adjustment is by means of the body tube running in a collar. This collar is connected to one of the three rods forming the stand. Fine adjustment is by means of a micrometer screw in the rod to which the collar is connected. There are a flat and concave mirror adjustable in a bracket. There is a simple stage.
The microscope has a Huygenian eyepiece with a focal length of 41.1 mm and a magnification of 6.1×.

With this microscope are three objective lenses:

• A ‘1/5’, signed ‘Patent Ross London no. 20140’ with correction collar for ‘dry’ and ‘wet’ (water immersion).
• An unsigned objective lens in a box signed ‘J.H. Steward / 406 Strand’ 2’’.
• an objective lens signed ‘J. Swift en Son / London’ 1’’.

The field of the ‘1/5’ objective lens is strongly curved, there is spherical overcorrection, the shape of the diffraction rings is irregular. When used with a 15× Huygenian eyepiece the diatom Pleurosigma angulatum is resolved into dots (‘dry’). Using water immersion (‘wet’) the lines of the diatom Surirella gemma are just not resolved.
The 1-inch objective lens shows a trace of astigmatism. The other objective lens is just good.

Accessories: a live box with spring rings.