The College of Optometrists

The BOA Museum has only a small number of microscopes although the first President and effective founder of the British Optical Association, John Browning, was noted for the ones he sold at his premises on the Strand, a few yards from the present College.

 

On the right is a late Victorian advertisement for one of Browning's 'Perfect' microscopes in brass and gun metal, supplied in a mahogany cabinet. The portrait of Browning is taken from the 1904 BOA Yearbook.

 

The 19th Century

 

In the first half of the nineteenth century the Culpeper-type of microscope remained popular. They were robust instruments that lasted well and because they looked attractive they were more often preserved.

 

Smaller instruments continued to be produced too. The picture to the left shows a Coddington Lens - a simple microscope with a condensing lens and a gold twisted loop handle. It is less than 4cm long and less than 2cm wide. The actual lens consists of a single piece of glass. Our example was sold by the optician Francis West some time between 1830 and 1844 (the dates he was at 83 Fleet Street). He continued working until 1859.

 

The drum microscope had been introduced by Benjamin Martin (as the 'pocket reflecting microscope') in 1738 but its simplicity and ease of use means that many Victorian and later examples exist.

 

This example of a drum microscope in a fitted wooden crate is probably early 20th century in date, but is reminiscent of Henry Craig's US-patented design of 1862.

 

Larger nineteenth century microscopes eventually abandoned the tripod design and returned to the now familiar 'pillar' type. Quality compound monocular and binocular microscopes were made by companies such as Dollond & Co, Smith and Beck, Ross and Powell and Lealand.

 

On the left are two pictures of a 19th century brass compound microscope made in Edinburgh by Alexander Adie (1775-1858), mounted on a wooden hinged case; thus in this example the foot of the instrument becomes the store for the accessories. Accompanying the item we possess a very old handwritten note: 'A List of Objects' including down of a moth, skin of a bug, knotted hair of a mouse and feather of a pheasant.

 

Towards the end of the century the finest instruments were made by Carl Zeiss in Jena, Germany especially following the improvements in optical glass introduced by Ernst Abbe (1840-1905) and Otto Schott (1851-1935) in the mid 1880s.

 

The 20th Century

 

These 42 specimen slides by C.M. Topping and others, include some labelled examples e.g. blowfly. The slides were used in the BOA examinations of the early twentieth century.

 

Other examples in the collection include Eye of Dytiscus (a diving beetle with a tiered retina), Eye of Beetle, Eye of Cockchafer (the European Maybug beetle), Eye of the Damsel Fly (they have small but obvious eyes) and a human crystalline lens in vertical section.

 

On the left is a section of the compound eye of a honey bee (Apis Mellifica). Glass slides like this are collectable in their own right. Even if they are not named the paper might still be recognisable as each was unique to its maker. Some of the best insect specimens were prepared by Fred Enoch. Some more unusual slides were produced by J.B Dancer featuring micro-photographs, for example portraits of prominent men, bank notes or the Lord's Prayer. (The Museum would particularly welcome the donation of any of these slides).

 

To the right is an example of a Challenge 'No 6' Microscope made J. Lizars, Opticians in Glasgow. This item is typical of a good quality but non-specialist microscope made in (and available for purchase from) a provincial optician's shop well into the twentieth century. It is of lacquered brass and black metal construction with a two-drawer eye-piece, specimen platform with clips and a v-shaped tripod base.

 

As the century progressed brass gave way to other, duller metals and plastics. This Carl Zeiss (Jena) example is one of the last pre-war examples of a microscope that was beautiful to look at. It dates from the 1930s and has a brass tube with black metal stem and stand. The mechanical stage is made of Bakelite and features a micrometer. Note the large focusing wheel and smaller fine focusing wheel. It has a triple nosepiece i.e. there are three brass objectives on a revolving changer (Zeiss D, Zeiss AA and one by Leitz). There is an Abbe condenser with variable diaphragm beneath the stage (including an empty ring intended for a blue glass filter). It was supplied in a fitted wooden crate with metal carrying handle. 

 

Microscopes were no longer the playthings of gentlemen but were mass produced for scientific laboratories, hospitals and schools. They were put through considerable use such that the present condition of many quite recent microscopes makes them look much older. Their crates were often thrown away and the instruments lived on a bench or shelf, with a dust cover if they were lucky. Our final picture shows a typical black-painted laboratory microscope of the 1950s. Antique collectors wouldn't give it a second look but the museum was keen to have it on account of its very ordinariness. It was made by the well-known firm of Cooke, Troughton & Simms Ltd of York. It features an adjustable stage and micrometer, rack-focusing mechanism, a horseshoe stand and 10X, 20X and 40X objectives on a revolving changer. There is also an Abbe condenser beneath the stage.

 

Up until the 1980s most microscopes had a fixed 'mechanical tube length' within the range 160-210 mm. Modern microscopes now employ tube lenses in the body which are corrected to infinity and which can interact with accessories without loss of image quality.

 

Today you can buy an educational  'toy' microscope for less than five pounds. This one, made in Hong Kong, was sold in a supermarket at Christmas 2003 for the princely sum of £4.43 complete with battery-powered lamp, specimen slides (including a pre-preapred slide of an insect wing) and adhesive labels for budding scientists to identify the fruits of their own field collecting. It has three objective lenses which can magnify up to 100X, 300X or as much as 600X. Although instruments such as these would be considered optically poor they aren't bad at all compared with what the gentlemen scientists of the past had at their disposal!