Compound achromatic student microscope




United Kingdom





Optical 1


Optical 2


Size of the box (h x b x d)

26.8 × 17.2 × 15.1 cm

Size of the microscope (h x b x d)

35 × 13.6 × 15.3 cm

Inventory number

SM 3


With the microscope goes its original box with lock and key. The cast brass foot of the microscope is mounted on a wooden board that slides into the box.
The microscope is inclinable between trunnions. Underneath the table a concave adjustable mirror and a revolving stop. Coarse adjustment works on the body tube which is approximately 190 mm long, fine adjustment works in the usual way on the nosepiece only by means of a lever and a micrometer screw.
There is a Huygenian eyepiece, its diameter is 26.8 mm, the focal length is 37 mm, the magnification is 6.75×.
The objective uses the modern RMS thread, as a consequence the microscope can be dated after circa 1860. The objective is made of three achromatic doublets lenses of 18.8 mm each. The cement of all three doublets was faulty, as a consequence it is not possible anymore to measure the total focal length and the quality of the objective.
With the microscope goes a bull’s eye condenser to illuminate the object from above, its focal length is 75 mm.
Further accessories are: tweezers, a pin, a live box and four preparations (Sections of Cork, Finland Whalebone, Sporules of Fern, Spicules of Sponge).
It is not yet clear whether Arnold actually made this instrument.