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MICROSCOPE AND MOUNTING KIT

MAKER: FIELD & SON

INVENTOR: W.P. MARSHALL (1869)

MODEL: 'NEW UNIVERSAL MOUNTING AND DISSECTING MICROSCOPE'

c. 1870's (1869 to about 1883)

DESCRIPTION HISTORY

Please Click On Any Picture for a Larger Version

DESCRIPTION:
field sigThe rectangular case contains the microscope and a variety of items for preparing specimens and making slides. The case measures about 17 cm X 17 cm X 25 1/2 cm. It weighs about 8 pounds (3.6 Kg) all packed. There is a swing latch and a barrel key lock. The microscope stands on a large solid mahogany baseboard. At the front of the baseboard is an inclined ledge to take a 3 x 1 inch slide with a centering target. The baseboard also has cutouts to hold each of the three simple lenses. The microscope is permanently attached at the rear via its A-frame rear foot of black finish, on a hinge. An oval signature plate is attached at the rear of the baseboard and is signed: 'FIELD & Co, SUFFOLK ST, BIRMINGHAM.'   This address was used by Field from 1852 onward. The third toe of the tripod is the tailpiece of the microscope and at its distal end is a small pointed pin to register on a choice of three holes in a brass plate in the center of the baseboard. The stage, main brass stage insert, and arm have a lacquered brass 'frosted'1 finish. The microscope is upright when the pin registers on the rearmost hole, and inclined at about 45 degrees when registered on the front hole. One additional position sits between the other two. A gimbaled mirror rides on a sleeve up and down the tailpiece. The microscope has a bar-limb construction with rack and pinion focusing. The main stage has one hole on each front corner to accept the stage-mounted bullseye or the stage forceps. A third hole is for the slide ringing table. The cutout in the stage measures about 81.5 X 58 mm. The compound tube is finished in lacquered brass. Unusually, its outer tube is a drawtube. There is one eyepiece and a single 3 part divisible objective fitting it. The three divisible parts of the objective are engraved 1,2, and 3. The arm can swing out of the way at will or be secured by tightening the knob.


Marshall-Field Microscopedrawers and accessoriesThe drawers and other fittings contain many accessories, most are original. These include accessories in the drawers, the compound tube, and the alcohol lamp. The lamp is housed in a compartment on the right side, held in place by a spring stay. The compound tube rests on a ledge under the left upper drawer. The drawer holds it in place, and must be removed in order to extract the tube from the case. The ringing table sits in a slot in front of and just below the compound tube. The other accessories are housed in the drawers. Chemicals are housed in a removeable tray.accessories


The case contains two deep drawers at the bottom and three shallow drawers above, one on the left and two on the right. These three shallow top drawers contain the components for making slides such as cells (for deep mounts) and labels, as well as the stage inserts and watch glasses. Among the other accessories are a scalpel (signed Baker, London), a spatula (unsigned), two dipping tubes, a small corked vial, and a test tube. The larger bottom drawers house the articulated stage-mounting bullseye condenser, a stage forceps, two coverslip clamps (clips), a generous supply of slides (edges polished), the dissecting trough, and a small box of coverslips.

chemicals chemicals A pull-out tray contains thirteen bottles of chemicals and stains, including turpentine and a bottle of alcohol for refilling the alcohol lamp. Three of these have brushes integrated into their cork lids, just as described in the original publication. The other bottles are for 'Goadby's fluid', 'distilled water', 'Goldsize', 'Glycerin', and 'Liquoir Potassae'. All these aforementioned bear labels that show they are original to the kit. Also included are three bottles of 'Dry Stain' by Flatters and Garnet including Gentian Violet, Brilliant Green, and Indigo Carmine, all with their contents intact. These types of stain preparations were not sold until late in the ninteenth century and are early twentieth century additions. The address for Flatters and Garnett on the bottles is 309 Oxford Road, Manchester dates from 1912. Three bottles have lost their labels, but one appears to be the original asphalte-varnish bottle; the turpentine, asphalte-varnish and goldsize bottles all have brushes integrated into their corks, just as described originally.

stage insertstrough stage insertstage bottomFour stage inserts were originally supplied. These stage inserts, shown to the left, are present of which two are original and two are accurate and realistic reproductions. The third is a modern replacement of the slide warming table insert. The fourth stage insert is a dissecting trough. Thanks to the courtesy of Mr Thomas Hopkins of the Museum of the History of Science at Oxford, who provided accurate measurements and other information about the original example of the trough (part of the RMS collection), I was able to produce an accurate replica of the dissecting trough. Just as the original, it is made of bent and soldered zinc, with a cork-lined bottom, and is painted flat black (except for the cork). It has a 1 inch diameter glass center in the bottom as well. Of the original two inserts, one is clear glass, the other brass with a central aperture that measures about 3.1 cm in diameter and has a ledge for a glass or other center. This insert has a decorative('frosted'1) finish on top, and is 3 mm thick on the edges along its length, but only one and a half mm thick otherwise. The thickened edges are about 2.5 mm wide. As shown to the right, wide-head brass screws are under each corner of the stage insert opening. The heads of the screws serve to hold the stage inserts only at the four corners. This lessens heat transfer to the main stage if the stage is heated (see below).

Another accessory originally supplied is a 'loaded cork.'  As described in John Quekett's Practical Treatice on the use of the Microscope, a loaded cork '...consists of flat pieces of cork of various degrees of thickness, that are covered over on their undersurface with sheet-lead of sufficient weight to make them sink in fluid...' As soon as a replica of one of these is constructed, it will be added to this page.


ringing attachment A slide-ringing table, in the form of a brass plate just slightly larger than a standard slide is present. It has a central target, and inserts through the main stage. This plate is affixed to a pointed steel rod on its underside which fits through the hole in the brass stage to register on a brass bearing in the baseboard allowing the ringing table to spin easily.


slide warming setupAs noted above one of the stage inserts is a solid brass plate, that was meant to serve as a slide-warming table. As in the original, the stage inserts make contact only with the screw heads at the corners. When the warming table is in use, the microscope is erected in the vertical position and the arm of the microscope, as well as the mirror are turned aside. With the mirror aside, the alcohol lamp sits beneath the warming table to heat the slide.


heating a watch glass At the same time, or separately if desired, the arm can be turned into the usual position, and a watch glass can be placed on the arm and gently warmed above the table; this allows evaporation of solutions from which crystals are formed for study under the microscope later.


watch glassWith the glass stage in place a large subject can be studied or dissected, or the watch glasses, which have flattened bottom centers, can be used for study of subjects in a liquid such as is pictured here with one of the simple lenses in place. Parenthetically, the regular brass stage insert could also hold a watch glass in its central aperture.


troughAnother interesting stage insert is the 'dissecting trough.'   Although this is a replica, it is made of the same materials and with the same techniques as the original. It is copied from the original example in the Museum of the History of Science, Oxford. It is made of single piece of sheet zinc, with a cutout in the center of the bottom covered by glass. This is surrounded by a cork lining of the bottom. The sides are bent up and the edges soldered. It was designed to accomodate a 1 x 3 inch slide. An additional small 'loaded cork' was also supplied. This is a small round cork weighed down by lead attached to the bottom which could be placed anywhere in the trough. As soon as a loaded cork replica is constructed it will be added to this page.


funnel The hole in the arm can also be used to support the bottles and a small funnel when refilling the bottles of chemicals. Lastly, the arm can serve as a wrist rest when dropping glue or asphalte-varnish onto the ringing table.

 



HISTORY OF THE MARSHALL UNIVERSAL MOUNTING AND DISSECING MICROSCOPE:
This microscope was first reported by W.P. Marshall in the Monthly Microscopical Journal(London), Volume 1, Issue 6, June 1869. Marshall was then the president of the Birmingham Natural History and Microscopical Society. He notes that the kit, which he designed, was 'worked out and improved by Messrs. Field of Birmingham' and was available for two guineas complete, except for the compound body and inclination mechanism which cost an additional guinea. As originally designed, the kit included four different inserts for the stage. Two of these were included in my original kit and include a glass insert and the standard insert with central aperture for routine use. Another which was not present when I obtained this kit is the slide warming table insert, which is a replacement. The other insert was a zinc trough lined with cork at the bottom and with a glass center. This zinc trough was to be used for dissecting, and was large enough to 'take ordinary slides and float dissected objects upon them.'   A replica of this trough is planned for the future.

The kit as originally designed was cubical in shape, not rectangular as my example above. In addition, instead of the sturdy handle in my example, it had a simple ring handle on top. Another example had matching thin full-handles on each side of the case which also came together when the case was closed to form a single thicker handle. These two earlier versions did not have the two larger drawers on the bottom.

This kit was referred to in several volumes of Carpenter's 'How to Work with the Microscope.' up until the English 1881 edition and the American 1883 edition. It is not shown in the next (7th) edition.

NOTES:
1. The finish on the main stage plate, the top of the arm, and the standard stage insert has a patterned finish which has been referred to as 'frosted' among machinists today, where the tip of a long file-like tool is used to scrape tiny patches of metal off the surface, in this case in small patches in random directions. This finish is not only decorative, but serves to hide minor blemishes and scratches from the surface in question.

  The author is indebted to Jim Solliday and Dr Joe Zeligs for some of the historical information about this microscope kit. I am also grateful to Phil Greaves for providing an image of one of the earlier versions of this kit. Lastly, I am especially grateful for information on the example in the RMS collection kindly provided by the Museum of the History of Science at Oxford through the very thoughtful courtesy of Mr Thomas Hopkins, without whose help an accurate replica of the trough would have been impossible.