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c. 1763




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Martin Universal Microscope Martin Universal Microscope 
left side  Parts of Martin Universal Microscope Accessories of Martin Universal Microscope

DESCRIPTION: This unsigned microscope, (unfortunately no longer in my possession), is identical to other signed examples, and is therefore attributed to Benjamin Martin. It is also identical to the type supplied with Martin's 'Optical Cabinet' (see below). The microscope is supported by three folding feet which form a tripod, above the center of which rises a ballister shaped turned pillar in top of which is a rectangular pillar. The rectangular pillar has a short extension at the top which jointed and attaches to the optical tube via a knob attached to a short extension of the tube itself. The optical tube can then be positioned in a variety of configurations including horizontal; it also allow a small degree of adjustment forward or backward. The stage has a central large opening and also a smaller opening to one side which accepts an opaque disk for examining opaque objects. There is also a keyhole slot on the stage which accepts a fishplate, and an additional hold in front is a simple compression fitting to accept the above-stage bullseye condenser. There is a provision for a glass vial under the stage. The plano-convex two-sided mirror sits in a fitting on one of the tripod legs. The eyepiece has a sliding dust cover. It has a 'between' lens with the convex side towards the eyepiece.It has the Hevelius screw-type focusing using a mechanism like the one used on microscopes by John Marshall starting in the 1690's and also by Cuff and others on the Cuff-type microscopes circa 1744 onward. Coarse focusing is achieved by loosening the set screw, and sliding the stage up or down, with graduations on the pillar to guide the user to a close starting point for focusing the various objectives. Once clamped at that location, the Hevelius screw is used to achieve fine focus. This instrument has a relatively short draw tube featuring a planoconvex field lens and the eyepiece features a planoconvex lens. This instrument has a conical snout. Accessories still with the instrument include a Bonani-type sprung stage, some ivory sliders, the stage bullseye condenser, a livebox that fits into the center of the stage, an opaque disk fitting into the smaller hole, a fishplate, three objectives, and a metal slider with glass insert to accept fresh material. There is not way to know if the slides are original to the instrument. The case is no longer extant.


Benjamin Martin was one of the first in the eighteenth century to use the term 'Universal' in 1738 to describe a microscope while he was still in Sussex. Martin is well known as a maker of a variety of instruments and in many cases was an innovator. He later went on to produce a Grand orrery (for Harvard), the five lens system used in his Universal Microscope, noted here, a weight driven table clock and an instrument called the "Heliostata" which combined the functions of a heliostat and a planetary clock. In 1742, Martin published a book called Micrographia Nova, in which he illustrated his second version of "Universal Microscope". This instrument, was "universal" in that the arm supporting the optical tube was on a ball-and-socket joint thus allowing the tube to be turned vertical or horizontal. He also supplied this instrument with a micrometer, something of a trademark on his early microscopes. By 1756 he was living in London. During his early years in London, he was apparently in fierce competition with his well-known peers not only as an instrument maker and lecturer, but also as an optician. This was particularly true in the spectacle trade where Ayscough published scathing criticisms next to Martin's own ads in newspapers of the time.

He went on to produce several varieties of 'Universal Microscope' which soon came to mean they could be used as simple, compound, or aquatic versions, and with both transparent and opaque objects. The 'aquatic' motion, allowed the arm to be moved so as to facilitate the observation of motile organisms in pond or sea water. Compared to the later models, Martin's first and second Universal microscopes, were quite simplistic.

The third version of "Universal Microscope", was announced in 1752; the exact construction of this instrument is not presently known since no illustrations were ever published. In 1759, after moving to London, he published an engraving of his all-brass "Universal Compound Microscope" in the Philosophia Britannica, the illustration of which is seen here. 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.

The next instrument was the one shown here. It was a transitional one which had only minor changes but set the stage for models to follow. Produced for sometime after 1759 and before 1768, it is virtually identical to the well documented and signed instrument sold to the famous scientist, Joseph Priestly, in 1767. The compound tube could be moved for and aft or removed completely to allow it to be packed into its relatively compact sharkskin-covered case. It could also be tilted so as to be aimed horizontally. This instrument must date from after 1759 when Martin first started producing instruments with the between-lens. It probably dates from before 1768 when he started to use rack and pinion focusing on a regular basis. Therefore the best estimate for a date of production is circa 1760-67 or about 1763. Features which differentiate this instrument from the previous instrument include the baluster-turned pillar, the round rather than square pillar base, and the fact that the knob holding the stage in place was this time identical to the ones which clamped the coarse focus and held the tube assembly on the arm. Finally, some examples of the instrument have conical snouts, while others have cylindrical ones which accept a lieberkuhn. The former may relate to Martin's development of a lieberkuhn holder which would attach to the front of the stage, a feature found frequently in his successive 'Universal' instruments and later on the Jones 'Most Improved' model (see the example of a Jones Most Improved in this collection). The microscope shown was often supplied with his biggest and most expensive 'optical cabinet' which he actually called 'a portable optical apparatus.' It was described at an auction after his death as 'magazine case of optical instruments containing a solar microscope a best compound ditto, a single ditto, and apparatus in a large fishskin case.' An example of one of these cases is shown in the accompanying picture. Incredibly, as he developed ill-health Martin's business was turned over to others; by the time he died, he was a poor man.


1. Millbum, JR: Benjamin Martin: Author, Instrument Maker and Country Showman. Supplement. Vade Mecum Press. London 1986.

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

The Engraving with the Newer Universal Martin Optical Cabinet with the Newer Universal