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c. 1930-PRESENT

McArthur Microscope variants

Please Click On Any of the Pictures Below for a Larger Version

John McArthur, a physician, designed a very portable microscope in the early 1930’s. It used folded optics in the form of prisms to miniaturize the optical path. He subsequently came up with many other features which made it a most practical instrument, especially in harsh environments. To the present day no one has come up with a better design for a portable microscope capable of functioning in virtually any climate. The idea grew out of his studies of slides of Malarial parasites and the need to bring a compact but high quality instrument into the field. Dr McArthur has said that the newly invented compact camera inspired him to design his compact microscope, which is ironic since about twenty years later, a camera company (Nikon), would put his design inside a 35 mm camera body.

wooden proto1932 metal prototypeThe initial prototype(left), was hand made of wood in 1930, and following that, the first metal version was made 'by McArthur' in 1932(right); this first metal instrument is part of the collection of the Royal Microscopical Society and is housed at the Museum of the History of Science at Oxford. The initial metal design, (right) as described in his 1934 article in the Journal of the Royal Microscopical Society, used full-sized objectives and used the top of the instrument as a stage. A mirror and condenser would then be on an extension of the main body of the microscope above the slide. The slide support rides on the stage forward and backward, providing a semi-mechanical movement. Since Dr McArthur was as physician, exactly how this first metal version was made is unclear, but it is likely he used a skilled machinist or company to assist him in construction. Only two of these were known to be produced and this version was apparently not sold commercially.

For a brief period in the mid-1930's, and shown in their 1935 catalog, Watson produced the watson McAMcArthur-Watson model(left), very similar to the first metal prototypes made 'by McArthur' just two or three years earlier. This form again used the less streamlined design for the bracket holding the condenser, again protruding higher above the main body of the microscope. It is unclear whether this version or the one in the next paragraph was sold first, but both were first produced about 1935. Some have argued that since this most resembles the original metal prototype, it came first. Against this is McArthur's own publications, that stated that Hearson was the first to make commercial McArthur microscopes. What is clear is that the model in the next paragraph was made at a time very close to this one.

third form McAApparently also in or about 1935, McArthur started to sell a slightly redesigned model similar to the prototype(left). This model still used full sized objectives and the stage remained at the top of the main body with the condenser and mirror assembly again protruding off the top, but this time in a more streamlined straight horizontal mounting. The semi-mechanical stage was no longer present, a fixed stage now standard. McArthur stated in his publications that Charles Hearson was the first commercial maker of his microscopes. The finish and form of this model does indeed suggest it likely was made for McArthur by Charles Hearson. It is unsigned(just like all known later Hearson Models). Like the slightly later Hearson's, the main body of the microscope has a polygonal housing for the eyepiece and a narrow shelf slants down from the top of the instrument next to the eyepiece housing.

hearson Mca
mcarthur light paths Starting about 1936, a model produced by Charles Hearson (left)incorporated special small objectives (made by Beck), and eliminated the projection off the microscope by placing the stage in the middle of the instrument. This allowed the condenser to be placed in the main body of the instrument, above the stage but not protruding unless in use. This is a much better arrangement, as it reduces the likelihood of damage or loss of parts. Compare the schematics here of the older model, and the newer version(right). According to Brian Bracegirdle, this production run was short and amounted to only about 12 microscopes, but the author is not aware of any proof of this as of May 2020. An example of this microscope with addition of a later special mechanical stage is shown on its own page.

slotted During WWII Dr McArthur was a p.o.w. During that time, he spent considerable time thinking about ways to improve his design. In 1945 he constructed, or had constructed, a model(left) which very much anticipated the final design of his microscope. It was constructed of one of the newly available lighter weight alloys. The one feature of that lighter model that did not endure was the knobs protruding from the sides to move the objective slider back and forth. This was quickly abandoned in favor of the older method of controlling the objective slider via protrusions at its front end. This latter earlier method was far less likely result in damage to the mechanism. As far as is known, this exact model was not produced for sale.

The maker(s) of the McArthur microscope between 1945 and 1959 is not known. The microscope was then made at various times, by McArthur's company, or under license from McArthur by different companies over the years. It is unknown who McArthur had assist him in producing his microscopes early on, or later for that matter, but as noted above, the finish on some of the earliest models suggest it might be Hearson. In fact, Hearson was in business until about 1960 and it is unknown when they last made McArthur microscopes. I have yet to find an ad for a McArthur-Hearson nor a Hearson catalog entry for one.

Early on there were no patents, as McArthur's intent was not to restrict the production of his microscope. In later years three patents appeared, including one for the illumination changer of the plastic Open University Model.

The McArthur microscopes featured a minimum of moving parts, no coarse focusing mechanism, and rugged yet precision construction which literally allowed their use at the South Pole as well as the hot and humid jungles of Borneo and the like. The use of a PTFE (polytetrafloroethylene, Teflon) bearing for the fine focus eliminated the problems with grease. Indeed, the elimination of the need for grease was one of the things that, to this day, makes the McArthur microscope what it is. Grease can freeze in cold environments, and liquifies leading to slippage in warm climates. Furthermore, it deteriorates, and eventually gums up with time, resulting in a completely frozen mechanism. Because of the invert`ed optical path design, the surface of the slide, with the subject side down, was always in the same plane, making coarse focusing 'automatic.'

The McArthur microscopes eventually had many accessories and configurations including phase contrast(as seen on the Cooke-McArthur in this collection), and darkfield illumination(also with the Cooke-McArthur in this collection), built-in electric illumination, a special gliding stage (with PTFE contact surfaces, see below) and others. Importantly, the precision of the instrument permitted high power oil immersion objectives to be supplied. Specialized ‘lying drop’ slides were also available.

From the time this microscope was first conceived about 1930, until the last quarter of the twentieth century, McArthur continued to come up with additional accessories, improvements, and new configurations, including even a fluorescence model. In some models the optical path was modified for special purposes, like surface inspection.   Early on, a 'friction type' of Mechanical Stage was integrated((McArthur, 1945), but apparently no example with this type is extant and no schematic of it was published. A Hearson example on this site has a miniature rack and pinion mechanical stage but its date of production is unclear; although very well made, the mechanical stage for this Hearson model has a different finish than the rest of the microscope, and its knobs have different knurling from the other parts of the microscope indicating this mechanical stage was an addition. The mechanical stage on this Hearson could pre-date the idea of the friction stage, or it is possible it superseded it or was a prototype, or even a custom-made addition. One thing that is certain is that its case is made of the same materials and is the same color as other known McArthur-Hearson Microscopes. Since the original case for it was obviously designed to hold it with the mechanical stage in place it was almost certainly all a Hearson product. In any case, mechanical stages for the McArthurs were apparently not popular, and were soon replaced by the manual stage with clips and later with the option for the 'Traversing Stage' as I noted above.

As time went on, the production of the microscope was, intermittently, licensed to other instrument manufacturers. The McArthur name continued to be attached, in various ways to these instruments. The subtle changes in the design over the years reflect progressive changes that improved the utility of the instrument. As I noted above, early models used standard objectives, using the top of the instrument as a stage, with the condenser then attached to a projection above the rest of the instrument. Starting in the late 1930's, the stage was lowered to the middle of the instrument through the use of shorter objectives, allowing the top of the instrument to support the condenser and light source, and shortly thereafter, other accessories. This made for an even more stable and sturdy microscope.

I have at this time, only an incomplete list of years during which various companies marketed the original McArthur microscope, and would appreciate any help on filling in the gaps. One of the confusing things is that during the time of production of the McArthur microscope, Cooke, Troughton, and Simms was a subsidiary of Vickers Ltd.  When the Vickers Ltd company acquired Charles Baker's business in 1963, the entire enterprise was renamed Vickers Instruments. Sometime during, or after that year, the inscription on the microscope made by that company was changed from 'Made by Cooke, Troughton and Simms...' to 'Made by Vickers Instruments...' .

It has been reported that from 1955-1959, and in 1987, McArthur Microscopes Ltd was the 'manufacturer,' and instruments from 1987, as is the 1987 model on this site, are clearly signed 'McArthur Microscopes Ltd'

Cooke-McArthur Scope Starting in 1959, (Vickers Ltd subsidiary) Cooke, Troughton and Simms (CTS) made McArthur microscopes 'under an agreement' with Dr. McArthur, the Model known as the ‘McArthur’ when labelled with Vickers as maker and 'Cooke-McArthur' when labelled with CTS as maker.  It has been reported they made them from 1959** until about at least 1969; in 1963, after acquiring C. Baker's microscope factory, Vickers instruments was formed. It is possible they continued until 1979; CTS ceased operations in 1988, but as mentioned above was a subsidiary of Vickers instruments! An image of an example of a Vickers-McArthur microscope is shown in the table below, courtesy of Dr Yuval Goren of Israel.   It appears identical to the CTS model and may indeed be the same instrument. Therefore, it is likely the name of Vickers Instruments was used on the instruments starting sometime after 1962. It has been reported to me by their archivist, that Vickers/CTS made relatively small numbers of McArthur microscopes during the years.

From 1979 until 1986, Prior made them, followed briefly by 'McArthur Ltd' again in 1987, and then by Kirk from about 1987 until 1993. Prior again took over the manufacturing after 1993, making only an additional 100 instruments before ceasing their production of the instrument.

Kirk-McArthur Microscope The McArthur model made circa 1988 until about 1993, under license from McArthur Microscopes Ltd, was the Kirk-McArthur, made by K.W. Kirk and sons. The Kirk models from this era had serial numbers 86/1 through 86/19, and then were numbered from 2001 through 2890. Number 2220 was from 1989. The Kirk-McArthur came in standard biological, phase contrast, surface inspection, and metallurgical models and could even be equipped as an interferometer for inspecting optical fiber cleavage. The surface inspection model and the metallurgical model could be acquired together as a kit combining the common elements of both with the two different optical tube assemblies added; this kit was known as the 'Engineering Model.'   The example of the Engineering model that I have came in a purpose-made blue plastic case with a foam lining, with cutouts for the microscope and accessories. I am aware that early McArthur scopes had a leather case, and the Cooke-McArthur had a clear plastic case.

As mentioned above, Prior again made the McArthur microscope for the second time, from 1993 onwards, but this did not continue for long.  An example of a Prior version is shown in the table below.  One of the objectives of my Cooke-McArthur is signed 'Prior.'

The maker(s) of the McArthur Microscope from the late 1930's though 1954, if any, is unknown to this author at the time of this writing. The table below summarizes the models and dates of manufacture by my best estimate; more accurate and complete information would be most welcome.

The following table contains information on almost all the variations in McArthur Microscopes produced on McArthur's own designs. Many thanks to my friends who kindly allowed me to reproduce their images for the instruments not in my collection, and especially to Yuval Goren for his images of the McArthur microscopes in the London Science Museum imaged with permission of the Museum and Yuval Goren 2018. Please click on the images for more information and images, where available.

c. 1930Wooden Prototypewooden McArthurJ. McArthurnonenone1
c. 1932First Metal Versionfirst McArthur Metal Microscope J. McArthurnonenone--?--
c. 1935-7(?) McArthur-WatsonMcArthur-Watson ScopeW. Watson & Sonsnonenone--?--
c. 1935(?)? First Sales ModelsMcA Metal J. McArthur
(via Hearson ?)
(?)c. 1938(?)-1940's(?) McArthur-Hearsonhearson Charles Hearsonnonenonec. 12(?)
(?)c. 1938(?)-1940's(?)McArthur-Hearson
with mech. stage
hearson Charles Hearsonnonenonec. 12(?)
c. 1945McArthurslotted McArthurnonenone--(?)--
c. 1946-1954McArthur? Unknownnonenone--?--
(?)c. 1955-9 &
also in 1987
McArthurmcarthur McArthur Microscopes LtdON FRONT:
And on Top:
none -?-
c. 1959-1962(?) Cooke-McArthur C-M Microscope Cooke, Troughton, and SimmsON TOP:
M130231' ,
 'PAT No 863102'
M130071, M130231, M130244, probably less than 1000
c. 1963(?)-69McArthur Vickers McArthur scopeVickers ON TOP:
'PAT No 863102'
M130553, ?--?--
c. 1970Open University ModelOU Microscope Scientific Optics Ltd, Ponswood Industrial Estate, Hastings, Sussex, England
Manufactured under License from Open University, Walton Hall, Bucks
Serial Number
01056, ?? over 9000
c. 1970Open University Model, Triple Objective OU triple objective microscope (?)Scientific Optics Ltd, Ponswood Industrial Estate, Hastings, Sussex, England
Manufactured under License from Open University, Walton Hall, Bucks
The Open University Model,
Patent applied for' 
c. 1970Open University Model, Polarized light versionOpen U. Pole Version Scientific Optics Ltd, Ponswood Industrial Estate, Hastings, Sussex, England
Manufactured under License from Open University, Walton Hall, Bucks
The Open University Model,
Patent applied for' 
c. 1983McArthur Microscope, Eritrean Health Model eritrean McArthur 'No 10'(?)On the front:
'EPHP, Designed by Dr John McArthur'
and on top:
'ERITREAN,PUBLIC, HEALTH,PROGRAM' with symbol of four interlocking arms.
c. 1979-1986,
Prior McArthurprior McArthur PriorSILVER ON BLACK:
c. 1988-1993Kirk-McArthur Kirk McArthur K.W. Kirk and SonsEmbossed on the front :
Serial Number Embossed on the back of the body
86/1-86/19, 2001-2890 820
c. 1988-1993Kirk-McArthur Engineering Model
(Metallurgical & Surface Inspection)
Kirk McArthurkirk surface K.W. Kirk and Sons---- ???none
1989Norland-Kirk, Interferometer Microscope interferometer McArthur Norland and Kirk and SonsSigned on the front :
2134, ?820
c. 1993--?McArthur ? Prior--?----?--100


In 1970 McArthur himself came up with a plan for a plastic version for the Open University. They needed 9000 units, and the mass production process cut the cost of making them to only 15 each. These were apparently manufactured by the Scientific Optics Ltd company in Sussex. There were at least two slight variations in the main model, and a special three-objective model instead of the usual two was also made. There was also a polarized light version with a small graduated rotating stage, an example of which is in this collection. Some of these plastic McArthurs were apparently made for individual sale, while others were sent in bulk to the Open University. The ones that were sold privately were sold 'under license' from the Open University. It appears that while at least some of the retail version examples have serial numbers, this may not be true for the Open University stock itself. At the same time, the standard metal version was selling for about 350 GBP- about $2000 in 2013. About 1983 another but smaller and more sophisticated plastic version was also made (in smaller numbers) for the Eritrean Public Health system; they have a design similar to the Kirk and Cooke Models, but are made of plastic. There are two examples of the plastic Eritrean model in the Science museum in London; one is missing its optics. I am grateful to the Science Museum and to Yuval Goren for providing the images of this model seen on this web site. The plastic versions are included in the above summary table.


Some of the elegant accessories that could be supplied with McArthur microscopes were described by McArthur himself in the microscopy literature, as referenced below. One of these is the lying drop slide, meant as an alternative to a hanging drop slide for pond life and sediment examination. McArthur pointed out the much easier use of lying drop slide, as the coverslip is fixed to the bottom of the slide and with the liquid above. Because of this design, the shape the fluid takes when lying is more uniform than a hanging drop, causing less distortion.

Another ingenious accessory is the 'Traversing' Glide Stage, which used blocks of PTFE (polytetrafloroethylene or Teflon), to provide a nearly frictionless traversing surface. The Traversing stage when pushed gently, can move very small distances in almost any direction, but when pushed more firmly, large changes in location on the slide are easily effected. The pressure of the PTFE upon the metal surfaces can be adjusted by little thumbscrews, to allow optimal tension for these movements.

McArthur patented a fitting for under the microscope, as seen on the Cooke-McArthur in this collection. This fitting had four threaded holes which could accept a variety of accessories and had removeable threaded inserts to accept, for example, a tripod; along with it was a specially designed tripod which could be used to simply raise the microscope, or raise it and keep it in an inclined position. The Cooke-McArthur in this collection is equipped with the underside fitting and a McArthur tripod.


Starting about 1950, several makers came up with their own variations, which in some cases defeated some of the essential features of the instrument and, in some cases, could not successfully substitute. Some of these are however high quality instruments. Among the best, (and most expensive) was the Nikon Model H, reviewed in a Micscape article here. manufactured in the 1950’s to 1960’s. This microscope which superficially resembles a 35 mm camera body, provides most of the features of an original McArthur, although the objectives rotate in a coronal vertical plane rather than use a slider. It is slightly larger than a classic McArthur. This model was used in Skylab. Variations included accessories for polarized light, phase contrast (the H3 model), and a wide variety of objectives. Disadvantages included some construction details which included more moving parts which were more susceptible to the elements. Much like the original metal McArthur microscopes, its price was its demise. They occasionally come up at auctions and usually sell for high prices, as they are collected by both microscope collectors and camera collectors. You can see my H3 version here.

In the 1970’s the Chinese came out with their version, the TWX-1.  This was made for military use, and was never commercially available at that time; it differs in that the optics are folded twice, and therefore slides are examined face up. It features both built-in battery-powered illumination, and a mirror that can be directed outward to use ambient light, or inward to use the built-in light. It has both coarse and fine focus adjustments, in keeping with its upright design, a disadvantage over the McArthur 'automatic focus'. The optics and construction of this microscope are overall quite excellent, though the mirror is a bit flimsy. The stage is the identical type of glide stage found on the Nikon H. It is the only folded portable I know of that has a hidden compartment to store an additional eyepiece. Its disadvantages include again more moving parts likely to suffer in extreme conditions, and the loss of the 'automatic focus' found on the inverted models. Considering the instruments that have come out of China, which have never been the best, this instrument, meant for use by the Chinese military, is built to a much higher standard and is an example of what high quality the Chinese are capable of.  Several reviewers of portable microscopes consider the TWX-1 as the best one ever produced.  As of the time of this writing (2016), it is offered for sale from time to time, on venues like eBay and the like. It is usually not inexpensive, and again, is worth its price for a superior instrument. If this instrument were new, it would likely sell new today (2016) for more than $2500.

Another maker of a clone was the Japanese maker Tiyoda, which made a simple version with a single objective (which could be changed by unscrewing it). The Tiyoda model features a flip-top and therefore resembles a large flip-top cigarette lighter.

Still another clone was the Loupe Microscope made by the Cogit optical company in France. It has a 'U-shaped' optical path utilizing four prisms. It is a most compact but fixed lens microscope of relatively low power. Very little is known about its history at this time and I would be grateful for information about it. I would like to thank Martin Mach for allowing me to link to the image on his website.

Between about 1983 and 2006, Swift, of San Jose California, had come up with a popular model, the FM-31, which was eventually copied and sold by Brunel (about 330 GBP in 2013) and Ted Pella (more expensive). Initially the illumination was by a rectangular flashlight, then by a Mini-Maglite, and more recently by an LED. There is a horizontally rotating objective turret on these instruments. All of these scopes were made in Japan, but the more recent versions can be had for as little as $250 (2016) new on eBay. The $250 version will not have a mechanical stage, and although a fairly good instrument, not as good as the original Swift FM-31. Even used, the brand name Swift FM-31 generally costs more, and rightly so, especially the older models with the black wheel vertical focus control, which are superior products. The FM-31 and their clones all included the use of a revolving triple nosepiece, coarser focusing controls, and are larger in size than the McArthurs mentioned above. Neither the original FM-31 nor its clones ever supplied an objective of greater than 40X power. This relates to the lower precision  resulting from their design.


Today variations of this microscope are still being produced, though none on McArthur’s exact plan. No currently manufactured McArthur-type microscopes have the same dimensions, plan, and quality that was associated with them when McArthur himself was involved.

For some time the Meade company made a cheap folded optics microscope (starting about 1990) on a slightly different design. With the plan licensed from the designer, Rick Dickinson, the ‘Readiview’ was intended for use by hobbyists and children, but its utility was limited to relatively low power work (80-160X), and the company has stopped making them as they never became popular.  For some time being it was still  available on the Meade site for about $100. It produces surprisingly good images, although there is some image shift with changing magnification. In 2004, production of an even simpler and lower powered version, the Trekker (35X) was started by another company. It is still in production and can be bought for about $40-50.

Inspired by McArthur’s work, a new non-profit company formed with the goal of producing a serviceable microscope at a price low enough that developing countries could afford them, but at the same time providing optics and accessories allowing high power work, particularly with malarial parasites. This is the ‘Newton Millenium Microscope’ by the Millennium Health Microscope Foundation, a not-for profit entity in England. It has a horizontal folding optical layout, resembling the Trekker and Readiview shapes. Costs are reduced mainly by using plastic parts. Unfortunately, the price had risen so that by 2013, it cost 607 GBP (about $928) fully equipped including an oil immersion 100X objective and mechanical stage, at least at the retail level.  I do not know what the cost would be to a nonprofit entity or a third world country. This microscope is still available from Lab Essentials in England. Currently (late 2018) the microscope sells for about 900 fully equipped. I wish to thank my friend and fellow microscopist, Dr Yuval Goren, for help with many aspects of this web page, and supplying many of the illustrations.

1950's-1960's'H' & 'H3' for the phase contrast modelnikon H3 NikonSigned on the oil access plate:'J.Pat., J. DES, OIL, Phase and on the plate on the other side 'Nikon, Japan, #####' ##### represents the serial number, an example of which is 42168(earlier models had an 'NK' Logo) --?-- --?--
2nd half 20th C. (after 1962)'VI' (10X obj) or 'VII' (20X objective)Tiyoda McArthur Tiyoda (also known as Sakura Finetechnical, now Sakura finetek)none (except on objective and eyepiece) --?-- --?--
c. mid 20th C.'Loupe Microscope'Cogit Loupe Microscope Cogit OpticalSigned:'Loupe Microscope Cogit' --?-- --?--
1970's'TWX-1'TWX-1 Chinese Army Microscope TaiYuan Optical Company of Shanxi Province, China signed in Chinese characters: 'Made in China' with the serial number 720953, 741280, ? about 1500
c. 1980(1980-1997)'Field Master' or 'FM-31'FM-31 Swift Instruments (San Jose, CA, USA)'SWIFT, FM-31, SWIFT INSTRUMENTS, INTERNATIONAL S.A. NO. 812436, PAT. PEND. JAPAN' 812436, ? --?--('hundreds per year')
1st Qtr 21st C.'Readiview'Readiview Meade Instruments-------- --?-- --?--
1st Qtr 21st C.'Trekker'Trekker ? Instruments-------- --?-- --?--
Starting 2013'Newton NM-1'Newton Microscope Cambridge Optronics for Millennium Health (England)-------- --?-- --?--


  1. McArthur, J (1934) A New Type of Portable Microscope. JRMS 54:182-5
  2. McArthur, J (1945) Advances in the design of the inverted prismatic microscope. JRMS 65:8-16.
  3. McArthur, J (1967) The history of the miniature microscope. PRMS, 2, Part 2.
  4. McArthur, J (1983) A New Form of Traversing Stage. JQMC 34: 592-596.
  5. McArthur, J (1985) The Lying Drop versus the Hanging Drop Preparation. JQMC 35:277-279.
  6. McArthur, J (1983) Automatic Focusing with the McArthur Microscope. JQMC 34:597-601.
  7. McArthur, J (1984) The Focusing Mechanism of the McArthur Microscope. JQMC 35:35-37.
  8. McArthur, J (1985) From Whisper to Vision- The Development of a Microscope over a Half Century. JQMC 35:405-.

* JRMS=Journal of the Royal Microscopical Society, JQMC=Journal of the Quekett Microscopical Club, PRMS=Proceedings of the Royal Microscopical Society.
**Recall that Hearson went out of business about 1960.