The Humble Hand or Demonstration Microscope

by Roland Mortimer, Brazil


 
 

Microscopes are usually heavy complicated instruments and can also be very costly. With this in mind, some manufacturers last century produced a simple hand microscope at a very reasonable price which could be used effectively in teaching. Some were slightly more complicated than others, having simple condensers attached or a special handle which could be clamped to the main tube, others could be attached to a base with mirror.
 
 


 
 

This example made by Zeiss is one of the simpler forms, no condenser or handle. It consists of a brass tube with eye-piece at one end and an objective at the other, much like a telescope. This tube slides inside a brass tube of slightly larger diameter to obtain focus. When focus is obtained, a simple locking ring secures the object in focus. A simple square stage with stage-clips is attached at the end of the outer tube, clips and slide being positioned outwards away from the observer. The whole instrument is nickelled, apart from the faces of the stage which are matt black.
 
 


 
 

The stage has a large circular recess to enable mounted slides with cover-glasses to be moved around. This instrument came to me with a No.3 (x5.5) eye-piece with focussing top lens and a brass Zeiss objective, 8mm, N.A. 0.65 (x20). I have even used wet mounts with this microscope and it gives good clear images. Using an old brass 1/12th oil immersion objective by Stiassnie and a x10 eye-piece the instrument resolved the dots on Stauroneis phoenicenteron and even the fine dots of Surirella gemma. Quite unbelievable for such a simple piece of equipment without diaphragm or condenser.
 
 

In use, the instructor/teacher would focus on the object to be examined, lock the ring to maintain focus and simply pass the microscope around the classroom or auditorium so each student could study the slide then pass it on. Since only daylight is necessary and no special accessories are needed, this also makes a fine compact field instrument. As can be seen in the photograph, it is signed, "Carl Zeiss, Jena" in beautiful hand-written script. Date, around 1900 or slightly earlier.

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Published in December 1998 Micscape Magazine.

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