Bone Optical Compendia, ca. 1720

Between the late 17th to the first half of the 18th century, pocket-sized optical compendia became popular. At their beginning, towards the end of the 17th century, they comprised a small Galilean telescope, often made of a bovine metatarsal bone and sometimes of wood. Items of this kind, which were found in archaeological excavations, all date to the 17th century and were found in mid-17th to early 18th century contexts, being all Dutch or English. Many of them are related to ships or other maritime contexts. Five were found in archaeological excavations near the port of Amsterdam. Others were found in the following shipwrecks: the Swedish ship Kronan (sunk: 1676); the British ship HMS Stirling Castle (sunk: 1703); the East India Company ship Hollandia (sunk in England in 1743) and Amsterdam, another East India Company ship (sunk in England in 1749). Another telescope of this kind is reported from the mid-18th century context at Notley Hall (18ST75), St. Mary’s County, Maryland, now kept in the Jefferson Patterson Museum.

These all point to some maritime context of these instruments. Because they were obviously not used for navigation, they must have been part of the private belongings of naval officers or merchants, used to satisfy their curiosity and interest in natural history during their journeys. Such interest must have been fueled by the emergence of maritime voyages involving some study of natural history, such as the travels of Willian Dampier (1651-1715) and the popularity of his memoirs. It can be also seen as a significant step in the rise of popular science.

All these finds only provide terminus ante quem for the production of these telescopes up to the second half of the 17th century, and may theoretically point to some maritime use. Because they were obviously not used for navigation, they must have been part of the private belongings of naval officers or merchants, used to satisfy their interest in natural history during their journeys. Such curiousity must have been fueled by the emergence of maritime voyages involving some study of natural history, such as the travels of William Dampier (1651-1715) and the popularity of his memoirs and a step in the rise of popular science.

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Bone Optical Compendium, ca. 1710-1720

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The instrument seen here is a combination of two instruments. It comprises two hollow bone cylinders having screw threads allowing them to be joined together. When combined, they form a fixed focus Galilean telescope (magnification: about 4X). When separated, a single microscope is exposed comprising a high magnification lens installed in small housing, facing a steel pin to which a flower or an insect could be speared for inspection (thus the term "flea glass", an English translation of the Latin name vitrum pulicarium). Later into the 18th century, more elaborate variations of this concept were made by Edmund Culpeper and perhaps some other English makers including, besides the telescope and "fleaglass" microscope, also a compass, a screw-barrel microscope with sliders, and a polyprism (an early form of kaleidoscope). The raw materials seem to have changed from bones to ivory and imported wood (lignum vitae or ebony).

Such items (referred to as "Little Perspectives") are advertised in John Yarwell's trade card of 1683, together with larger telescopes and optical compendia.

These pocket telescopes developed towards the end of the 18th century into such optical compendia, combining the telescope, a "fleaglass" microscope and/or a livebox, and in more complex forms also a polyprism, compass, sundial, and a screw-barrel microscope, were intended for amusement, not for true research, but their small size and versatility made them handy for seamen along their journeys. However, the telescope function was useful for short distances (hence functioning as a Long Working Distance {LWD} microscope), or even as a seeing aid for the shortsighted. In the caricatures of the period, King George III is often seen using his pocket telescope to view a speaker.

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Ivory Optical Compendium, ca. 1750

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This type of handheld microscope compendium (sometimes referred to as "Acorn Microscope" or Granger type), was popular among naturalists during the second half of the 18th century. They were made of ivory, ebony or brass, and roughly looked like acorns, hence their popular name. The domed cap is covering the higher magnification "flea glass", namely a lens installed in small blackened ivory housing, facing a steel pin to which a flower or an insect could be speared for inspection. When the dome and the lower covers are removed, a lower magnification loupe is revealed.
Inside the loupe a "live box" microscope is stored, having a compartment with glass front to store small fauna or flora and a mid-range magnification loupe to view it.

These microscopes are often dated to the 18th century, though G.L'E Turner (1989) suggested that they may very well continue into the beginning of the 19th century. However, this view ignores issues such as terminus ante/post quem and in reality there is no evidence for the production of these compendia after the 2nd half of the 18th century. Obviously, some of these were further used by some into the early 19th century or retailed by traders, but their production seemingly ended with the introduction of Adams' botanical microscope around the 1780's. They are always unsigned but looking at the specimens shown in the literature, there seems to be some variation in shapes though the overall design is conservative.

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References: Talbot, S. 2011. Culpeper's Cylinders: his Optical Compendia circa 1700-35. SIS Bulletin 110: 23-27; Greenwich: NAV1555; NAV1663, NAV1492 (wood), SML: A35405, 1918-91, 1918-272, 1690-1710, 1938-740 (wood); MHS: 53609 (Culpeper compendium); Billings: P. 197, Fig. 379, AFIP 518853-66-6274; Lentz Col.;.