Benjamin Type Microscope

Benjamin Martin Microscope

[Text Discription Below]

20016

A Fine Benjamin Martin Universal Compound Microscope:

English ca. 1759.  Unsigned, as was typical of many of Benjamin Martin's microscopes.  Benjamin "1" Martin (1704-1782) was a well known teacher and scientific instrument maker working in London during the 18th century (w 1738-1777).  He is recorded to have worked in Chichester from 1736-1740, and then in London, at various addresses on Fleet Street, including his private residence (1).  According to the much cited review by Dr. Barry Sobel (2), this is the third version of Martin's "Universal Compound Microscope."  Martin announced his third version in 1752, but no illustrations were ever published, so its exact construction is unknown to history.  In 1759, assuming some improvements were made, he published an engraving of this microscope in the Philosophia Britannica.  A picture of this engraving is seen in the  accompaning photographs (3).  Notable by comparison, is the simple limb with square base above the splayed tripod feet.  This is identical to the configuration of the present instrument, and pre-dates the microscopes with turned balaster limbs which were introduced in ca. 1763.  This instrument is made of lacquered brass and stands 32 cm high.  The main optical tube attaches to the top of the limb via a winged-screw compression bracket.  The optical tube is complete with dust shade and is composed of three optical elements and a threaded section for changing objectives.  The entire tube dissambles by several threaded sections for lens access and maintenance. Course focusing is by moving the wing shaped stage to preset stops marked on the limb.  Fine focusing is then achieved by a finely threaded rod which moves the stage in small increments until the specimen is brought into focus.  There is a gimbled concave mirror attached to one of the splayed tripod feet.  The accessories include four un-numbered objective lenses, a liberkuhn which attaches to one of the objectives by threaded section, a fishplate, a Bonanni spring stage, a live box, and stage mountable tweezers and condensor.  There is an ivory slider with talc box for sample preparation and a brass slider for aqueous samples.

"This was his first instrument with the innovative, (but as he admitted, not original), 'between-lens'.  Until that time, as first described by the Italians, many makers used a field lens to create a larger field of view, but Martin was the first in the eighteenth century to revive the use of a 'between lens.'  It is a planoconvex lens of long (4-5 inches) focal length which essentially forms the rear element of all the objectives.  It was placed at the top of the snout which came to be known as 'Martin's Pipe' because of its cylindrical form in many of his microscopes.  The microscope featured a Hevelius-screw type of fine focus (as in the Cuff model of 1744), and a winged stage which could swivel in arc, preserving the function found in his second universal microscope" (2).

The microscope dissambles and stores into a fitted, rayskin covered wooden box.  The box is fitted with a mortised lock, with key, and a ring pull attached to the lid.  The inside reveals fitted compartments lined with red velvet, and the exposed wooden perimeter painted red. 

Condition:

The condition is very fine throughout.  The microscope is fully functional, and retains most of its period lacquer finish.  The optical system is fabulous.  A full complement of accessories are present, which are very likely original to the set.  There is some expected age related delamination to the silvered mirror.  The rayskin covered case is sound with only very light storage wear.  Overall, excellent condition considering its age of 265 years.

Provenance:

       Dr. Murry MacKinnon Collection.

Bibliography:

1.  Clifton, Gloria (1995) Directory of British Scientific Instrument Makers 1550-1851; ISBN [0-302-00634 6] p. 181.

2.  For an online review of the Benjamin Martin Microscopes by Dr. Barry Sobel, please see:  [microscope-antiques.com/martinuniversal.html].

3.  Millburn, John (1986) Retailer of the Sciences: Benjamin Martin's Scientific Instrument Catalogs, 1756-82. Vade-Mecum Press, London. p. 70.

4.  Turner, Gerard L'E (1989) The Great Age of The Microscope (The Collection of the Royal Microscopical Society Through 150 Years) 
ISBN [0-85274-020-4]; p. 56-59.

5.  Benjamin Martin's trade card is reproduced here by permission from the Science Museum.