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Compound drum microscope

Maker

UNKNOWN

Country

United Kingdom

Signature

Unsigned

Category

Microscopes

Optical 1

Compound

Optical 2

Non-achromatic

Size of the box (h x w x d)

8.5 × 28 × 15 cm

Size of the microscope (h x w x d)

25.6 × 6.6 × 7.5 cm

Inventory number

SM 23

Description

With the microscope goes its wooden box, the inside of which is lined with red velvet.
The microscope is built as a drum microscope, coarse adjustment is by sliding the body tube in its sleeve. Fine adjustment is by rack work. In the drum is a concave mirror which can rotate about its axis.
The integral spring stage has provision for both normal object slides and a glass tube for observations of live animals in water.
The microscope has a three-lens eyepiece with two eye lenses and a field lens, separated by a diaphragm. The focal length is 48.8 mm, the magnification is 5.1×.
There are six objective lenses and a Lieberkühn which has no lens anymore.
The objective lenses have been investigated on the microscope itself.

Objective 1 2 3 4 5 6
Focal length (mm) 5.5 13.95 20.20 24.04 28.61 35.06
Magnification 137.8 49.2 33.5 26.9 21.65 16.4
Numerical aperture 0.15 0.053 0.043 0.042 0.043 0.039
Resolving power (µm) 3.75 7.25 9.5 9 11 9.5
Star test coma good good good good good

Accessories are: five object slides made of bone and a live box. In the box a lens for incident light, an object clamp and a pair of tweezers, these are probably not original.