Accession No

4568

Brief Description

compound microscope, possibly achromatic, with mechanical stage, by E Leitz and W. Watson and Sons Ltd., German and English, 1905 and circa 1910 [mechanical stage]

Origin

Germany; Wetzlar [Ernst Leitz]; England; London [W. Watson and Sons Ltd.]

Maker

Ernst Leitz W. Watson and Sons Ltd.

Class

microscopes

Earliest Date

1905

Latest Date

1905

Inscription Date

1905

Material

metal (brass, oxidised brass, white metal); glass; wood; cloth (velvet); paper (card and one other)

Dimensions

box height 345mm; breadth 178mm; depth 188mm microscope height 274mm; breadth 115mm; depth 155mm

Special Collection

Provenance

Donated on 29/10/1996.

Inscription

‘E. Leitz Wetzlar
No 77729’ (foot)
‘W. WATSON & SONS LTD.
LONDON.’ (mechanical stage)
‘E. Leitz
Wetzlar’ (two of the eyepieces and two of the lids for the objective holders)
‘3
E.Leitz; (on 1st objective)
‘7
E.Leitz
Wetzlar’ (2nd objective)
‘ 1
1 2
Oil Immersion
E.Leitz Wetzlar
Apert.
1,30’ (on 3rd objective)
‘ESTD 1866
F. ROBSON & CO
OPTICIANS
NEWCASTLE-upon-TYNE’ (plaque inside box)
‘C.ZEISS JENA’ (on nosepiece)

Description Notes

Black painted horseshoe base. Pillar to tongued joint. Brass pillar with knurled screw, with conical cap for fine focus. Swinging plano-concave mirror on articulated limb from hinge. Circular stage with screws for lateral and longitudinal adjustment. Shaped bar to limb with rack and double screws either side for coarse focus. Draw tube divided [13] - 19 numbered by 1 subdivided to 0.1. Rotating triple nosepiece. Substage with condenser and iris diaphragm. Fitted wooden box with sliding drawers contains mechanical stage by Watson (hexagonal clamp with 2 knurled brass screws for attachment to stand. 2 further screws operate longitudinal and lateral motion. Steel clips to hold slide in place); 3 eyepieces marked ‘1’, ‘3’, and ‘4’; 3 objectives (one for oil immersion); 1 stage clip; instruction leaflet for testing oil immersion objectives. Box with white metal hinges and key. Brass lock and carrying handle.

Corrosion on stage and pillar; Incomplete (missing an objective) (21 parts counted, excluding small box which could not be removed)

References

Events

Description
When light travels through an ordinary lens each colour is bent through a different angle. In a microscope this causes what is known as chromatic aberration, whereby a spectrum of colours will appear around the image being viewed. Chromatic aberration was a big draw back when using early versions of the compound microscope.

Chromatic aberration was overcome due to the important work by Lister in 1830 who developed the achromatic lens for microscopes. The new type of lens prevented colour separation by combining two lenses made of different types of glass. The first lens that light passed through would split the colours and the second lens acted to bring the colours back together again. This produced a much sharper and clearer image than was previously achieved.

In the Victorian period the achromatic microscope became a vital tool in medical and scientific research. Improvements to the optical performance of the microscope saw developments in the design and construction of the microscope. The microscope became sturdier and could focus to a finer level.

Scientific instrument makers in the Victorian period who improved the rigidity of the optical tube and the focusing ability of the achromatic microscope include Andrew Ross, James Smith and Hugh Powell.

FM:40257