Microscopy Primer
Light and Color
Microscope Basics
Special Techniques
Digital Imaging
Confocal Microscopy
Live-Cell Imaging
Microscopy Museum
Virtual Microscopy
Web Resources
License Info
Image Use
Custom Photos
Site Info
Contact Us

The Galleries:

Photo Gallery
Silicon Zoo
Chip Shots
DNA Gallery
Amino Acids
Religion Collection
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery

Granger Brass Acorn Simple Microscope

Granger's three-in-one brass magnifier, known either as a flea or acorn microscope, typifies one style of very popular pocket microscope commonly produced during the late eighteenth and early nineteenth centuries. The brass and glass magnifier illustrated below was redrawn from photographs of the original 1790 instrument, which was described by Gerard Turner in his book The Great Age of the Microscope.

The shape and size of the totally encapsulated compact microscope resembles an oak tree's acorn in some ways, and is thus the source of its popular nickname. Like contemporary designs fashioned in brass, bone, wood, or ivory, the portable optical instrument functions either as a simple or compound microscope. The domed screw cap houses a small, high-power lens and a vertical pin for mounting specimens, such as a flea, in an apparatus that was made popular in the late seventeenth century by the British instrument maker and microscopy pioneer Edmund Culpeper. Examining small insects or other objects required the microscopist to hold the single lens very close to the eye, while the specimen was viewed at a precise distance from the eye lens. The base of the acorn microscope was shaped to fit an observer's hand. When the base is unscrewed, a slightly tapered, removable brass unit reveals a lens and a live cell or compressarium. Small objects or live specimens are held between a flat and plano-concave glass disc in the compressarium. The third imaging option available to the microscopist is a bi-convex lens that is used as a 8x magnifying glass, or hand magnifier, and which is located in the remaining body of the optical instrument.

The illustrated acorn microscope was described in 1906 in the Journal of the Royal Microscopy Society. It is die stamped with the phrase "R. Granger, Tettenhall, 1790" surrounded by a circular border of leaves. Tettenhall is a small village in Staffordshire, England. The brass pocket microscope is unusual for an acorn microscope from the turn of the eighteenth century, primarily because it is both signed and dated. Similarly designed microscopes that are contemporary to the illustrated brass pocket instrument are usually very hard to date or attribute to a particular craftsman. The Royal Microscopical Society received the versatile and highly portable microscope in 1906.


Questions or comments? Send us an email.
© 1998-2019 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Friday, Nov 13, 2015 at 02:19 PM
Access Count Since January 8, 2003: 16349
For more information on microscope manufacturers,
use the buttons below to navigate to their websites: