CARY-GOULD MICROSCOPE

c. 1835

Unsigned, but by Cary

Serial Number:None

MODEL: Gould's Improved Pocket Compound Microscope

DESCRIPTION

HISTORY

DESCRIPTION

The instrument is nearly complete when compared to figures in Gould's booklet. The case measures a mere 3 3/16 x 3 15/16 x 1 7/16 inches in thickness. The case is made of mahogany, and lined in a dark purple velour with flaps serving to separate the layers. The arm can be used with the stage forceps and one of the objectives as a hand held simple microscope. The outfit includes:

1. The pillar, screwing into a metal fitting on the front edge of the lower part of the case, supporting a stage focused by rack and pinion; the stage has a sprung slot beneath to accommodate bone sliders and has one hole to accomodate accessories to the right side.*
2. The arm attaching to the erected pillar with a thumbscrew, and is thereby fixed not allowing an 'aquatic' or swiveling motion.
3. One integral eyepiece which is integrated into the optical tube by screw thread.
4. A single sided substage mirror, its pin fitting into the pillar.
5. A set of four objectives, of which the fourth is the black disc high power objective mentioned in Gould's tenth edition booklet and said to have a focal length of 1/30th of an inch.
6. A circular brass depression trough called the 'moveable piece'.
7. A small round livebox ('object box') fitting into the stage.
8. A stage forceps which can fit not only on the stage, but also onto the arm, which when attached to the arm alone, as shown to the right, forms an integral hand-held simple microscope.
9. Dissecting instruments include a small ivory-handled scalpel, a small ivory-handled dissecting needle, and small brass tweezer; the tweezers has the unusual addition of a little spoon on the end of the handle, the purpose of which, according to Gould in the description given in the tenth edition of his book, was to scoop up a small drop of pond water for examination with the two pieces of glass sealed together.

*some Gould Pocket microscopes have only one hole for accessories on the stage, others have two holes, one on either side.

Gould's own description and figure from the tenth edition are seen here.

Note that missing from this example are the Brush for 'obtaining mites' and the like, the Test Slide, and the Two pieces of Glass sealed together for holding a drop of water which is identified as 'P' in the figure. Joe Zeligs was kind enough to provide images of examples of the water slide, and also what is likely the test slide. The known examples of the 'glass water slide' (trough)measure about 1.2-1.4 X 0.55-0.65 inches in length and width, being about 0.15 inches thick and with a gap between the slides of about 0.015 inches. These slides are very crudely cut and the application of the wax also quite crude. The edges of these slides are not polished. A few examples of this microscope are also known to have a tiny freestanding bullseye condenser accompanying it, also lacking from this example. The parts of this microscope, and its accessories, all disassembled, are shown laid out at the bottom of this page.

The optical elements include the top eyepiece, cylindrical spacer containing a diaphragm, the conical tube which has another optical element at its top and a diaphragm at its bottom, and the objectives; all except the highest power objectives are in brass cells which screw on, while the highest power is in a black-painted brass disk which drops into the arm ring, rather than screwing on. According to Gould, this last high power objective was to be used alone, not with the compound tube.

HISTORY OF THE GOULD IMPROVED POCKET COMPOUND MICROSCOPE

This is a classic in the world of microscopes. The design is attributed to Charles Gould, a workman who was employed by the Cary company and described in his book, published in many editions, entitled: The Companion to the Microscope and a description of C. Gould's Improved (Compound) Pocket Microscope... London: Sold by W. Cary, 181 Strand. The title continued, and changed over the years as can be seen in the table listing many of the different editions. Although the title was as noted, the figure in the booklet often described it: Answering the purpose of the single, Compound, Opaque, & Aquatic Microscope. This type and size of microscope was first developed sometime in the 1820's and the first edition of Gould's booklet was said to be published no later than in 1826(as reported in the Mechanics' Register for that year), yet by 1829 it was in its sixth edition. Both the fifth and sixth editions were published in 1829. Click here to see an enlarged image from Gould's 1835 Booklet. The earlier complete 1829 sixth edition may be found here on the Microscopist.net website. Note the change in the title with the later 1835 tenth edition to include the compound, oxy-hydrogen and solar microscopes, although most of the information and all of the engravings reflect the use of the original 'Improved Compound Pocket Microscope.' Indeed the title frequently changed with each subsequent edition as can be seen in the page devoted to Gould's books; this page also addresses the evolution of this little instrument and especially its included accessories, over twenty five years or more.

Gould soon claimed many makers were producing a similar, but inferior copy of his invention, and supplying with it a copy of Gould's Booklet. He felt that by supplying a copy of his booklet with these copied microscopes the purchaser was misled into believing it was a Cary-made Gould microscope that accompanied the booklet. On pages 3 to 4, in the 1835 tenth edition of his booklet, he stated that the authenticity of a Cary-Gould microscope could be confirmed by examining test objects with a recently supplied high power lens in a black disc (seen in place on the instrument, as pictured to the left, and alone, below that). This disc is shown starting no later than the 1832 edition, and was not pictured in the 1829 editions. Apparently Gould believed the imitators could not produce such a fine high power lens. Even though this example is unsigned, it contains the high power disc in the case. In a side by side comparison, you will note that the figure from his 1829 sixth edition does not picture this new accessory, but it is seen in the figure from the 1832 eighth edition, and also 1835 tenth edition, and is labelled as number 4. This little lens included with the microscope described here, is not commonly seen and this may be more because, being so small and black in color, it is easy to lose, rather than the fact that it was not supplied with the microscope in question. It indeed does have a very short focal length, and my example does produce a good image. It can be used alone or even with the compound body, but focusing with only the coarse focus supplied is very difficult, and moving the specimen is even more problematic to say the least! This would have been easier with the version of the Cary-Gould instrument which had a both a mechanical stage and a fine focus, also seen on this site. For more on the Gould Test Objects, including his engraving of all the test objects he suggested, please click here.

As time passed, different versions of a similar microscope were produced, and several are found in this collection. The small model pictured here is however, the original size and type, and the only model featured in Gould's little books; one could easily argue that only this small pocket model should be called a 'Gould' Microscope; to my knowledge he never associated any of the similar larger instruments with his name, although I would welcome evidence to the contrary from any reader. The black disk with high power lens dates this example to about the time of Gould's later editions, circa 1835 and later.

GOULD'S BOOKS AND CHANGES IN THE GOULD MICROSCOPE OVER THE YEARS

Gould's books illustrate the evolution of the Gould Improved Pocket Microscope over the years and a review of changes in the books and the microscope over these years is reviewed here.

The author is greatful for the help of Joseph Zeligs who added greatly to the information found here and generously supplied pictures of the glass slide trough and test slide from his own personal collection; this page and its links owe much to the efforts of Dr. Joe Zeligs. In addition, I would like to thank Dr Brian Stevenson for providing a copy of the sixth edition of Gould's book on his wonderful website, 'Historical Makers of Microscopes and Microscope Slides'. I also owe thanks to Dr. James McCormick who confirmed the existance of the test slides and their contents in his own collection.