Naturalist John Hill Named Tooth Shell Constellation Dentalium in 1754

Summary: English naturalist John Hill named tooth shell constellation Dentalium in his 1754 astronomical dictionary, Urania, or, A Compleat View of the Heavens.

John Hill's Dentalium the Tooth Shell constellation (left lower-center) inhabits the southern celestial hemisphere's fourth quadrant (SQ4), in the neighborhood of Aquarius the Water Bearer, Capricornus the Sea Goat and Delphinus the Dolphin, and shares the quadrant with two other Hill-invented constellations, Anguilla the Eel (center left) and Pinna Marina the Mussel (upper left): Ultima Thulean, CC BY SA 4.0 International, via Wikimedia Commons

Eighteenth-century English apothecary, naturalist and writer John Hill introduced Dentalium the Tooth Shell constellation in his astronomical dictionary, Urania, or, A Compleat View of the Heavens, published in 1754.

Hill (1714-Nov. 21, 1775) introduced the molluscan constellation with the standard epithet that he uniformly applied to all 15 new constellations in Urania. "A conſtellation offered to the aſtronomical world," he began, adding "and compoſed of certain unformed ſtars near the ſhoulder of Aquarius." The "out-lines" of the starry arrangement impressed as "a ſhell-fiſh, an inhabitant of the ſhallow ſeas, and is frequent in the collections of the curious." He traced the genus name, Dentalium (Latin: dentālis, “dental," toothlike shape), to the shelled marine mollusc's "reſemblance . . . to the tuſk of ſome animal, and is deſcribed by all who have written on natural hiſtory."

Although describing Dentalium the Tooth Shell as "a ſmall conſtellation," Hill appreciated the ratio of stars to space in its location. He assessed that "for its extent, it contains a conſiderable number of ſtars."

Four constellations neighbor Dentalium. Now obsolete constellation Antinous the Beloved of Hadrian, Aquarius the Water Bearer, Capricornus the Sea Goat and Delphinus the Dolphin surround the Tooth Shell. "Its open part, or mouth, is towards Antinous, and its extremity, or point, towards Aquarius." Dentalium's point nears the Water Bearer's shoulder while "the lower part of the bend of the ſhell is alſo near the hand, and a part of the robe." Antinous, the Dolphin and the Sea Goat associate with Dentalium's "open part." One of Antinous's hands nears it. The Dolphin's "tail, or lower part" and the Sea Goat's head are positioned "at ſome diſtance," almost equidistantly, over and under, respectively, Dentalium's "open part."

John Hill's Dentalium the Tooth Shell constellation emerges from unformed stars near Aquarius the Water Bearer in the southern celestial hemisphere's fourth quadrant (SQ4); John Hill, Urania, or, A Compleat View of the Heavens (MDCCLXVIII [1768]): via Internet Archive

Hill tallied Dentalium's "conſpicuous ſtars" at 15. They formed four clusters "at ſome diſtance from one another."

He delineated the placements of the clusters on the celestial Dentalium. The first cluster, comprising five stars, "marks the mouth, or opening. One is placed at each limit of the ſhell, but theſe are both ſmall ones." Between the two end stars occur three larger stars, of which two are "nearly upon a level with one another, and the third is lower on the ſhell." Above the Tooth Shell's middle distantly hovers a cluster of three stars, of which the largest perches above the other two. Another cluster of three are positioned equidistantly beyond Dentalium's middle as markers of "each out-line, and . . . the midſt of the ſhell." The fourth cluster is composed of "two leſſer cluſters, of two each." The first two stars, which are small and distantly placed with each other, "stand at a ſmall ſpace from the extremity of the ſhell." The second set of two stars occur close together "very near the point of the extremity: theſe are juſt over the ſhoulder of Aquarius; and the third cluſter is almoſt immediately over his hand."

Eight of Dentalium's 15 "conſpicuous ſtars" are identified by David Harper, once an astronomer specializing in celestial mechanics and positional astronomy but now a genome researcher, and his wife, astronomer L. (Lynne) M. Stockman, in "Dentalium -- The Tooth Shell," posted on their Obliquity website. Six stars reside in Aquarius the Water Bearer: 4 Aquarii (abbreviated 4 Aqr), 11 Aqr, 12 Aqr, 15 Aqr, 16 Aqr and 21 Aqr. Two belong to Aquila the Eagle: 69 Aquilae (abbreviated 69 Aql) and 71 Aql.

Dentalium occupies the southern celestial hemisphere's fourth quadrant (SQ4). The celestial Tooth Shell shares the quadrant with two other Hill-invented constellations, Anguilla the Eel and Pinna Marina the Mussel.

The International Astronomical Union (IAU) has not recognized Dentalium as an official constellation. Accordingly, Dentalium does not appear on the list of 88 IAU-approved constellations. Categorization as an obsolete constellation, however, does not dissociate Dentalium from its starry components. The asterism may still be discerned near Aquarius the Water Bearer's left shoulder.

John Hill equated his Dentalium the Tooth Shell constellation with Earth's Dentalium genus of shelled marine molluscs, known as tooth shells or tusk shells; depictions of Dentalium species (lower right), in John Hill, An History of Animals (1752), Plate 7, opposite page 139: Public Domain, via Biodiversity Heritage Library

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

John Hill's Dentalium the Tooth Shell constellation (left lower-center) inhabits the southern celestial hemisphere's fourth quadrant (SQ4), in the neighborhood of Aquarius the Water Bearer, Capricornus the Sea Goat and Delphinus the Dolphin, and shares the quadrant with two other Hill-invented constellations, Anguilla the Eel (center left) and Pinna Marina the Mussel (upper left): Ultima Thulean, CC BY SA 4.0 International, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Southern_Hemisphere_Hill's_Constellations.png

John Hill's Dentalium the Tooth Shell constellation emerges from unformed stars near Aquarius the Water Bearer in the southern celestial hemisphere's fourth quadrant (SQ4); John Hill, Urania, or, A Compleat View of the Heavens (MDCCLXVIII [1768]): via Internet Archive @ https://archive.org/details/bim_eighteenth-century_urania-a-new-astronom_hill-john-m-d-calli_1768/page/23/mode/1up; Ultima Thulean, CC BY SA 4.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Dentalium_Constellation.jpg

John Hill equated his Dentalium the Tooth Shell constellation with Earth's Dentalium genus of shelled marine molluscs, known as tooth shells or tusk shells; depictions of Dentalium species (lower right), in John Hill, An History of Animals (1752), Plate 7, opposite page 139: Public Domain, via Biodiversity Heritage Library @ https://www.biodiversitylibrary.org/page/56071345; Biodiversity Heritage Library (BioDivLibrary), Public Domain, via Flickr @ https://www.flickr.com/photos/biodivlibrary/50374595528/

For further information:

Harper, David; and L. (Lynne) M. Stockman. "Dentalium -- The Tooth Shell. Unofficial Abbreviation: Den. Genitive: Dentalia. Origin: John Hill." Obliquity > Sky Eye > The Constellations > Extinct Constellations.
Available @ https://www.obliquity.com/skyeye/88const/Den.html

Hill, John. "Dentalium." Pages 120-121. An History of Animals: Containing Descriptions of the Birds, Beasts, Fishes, and Insects, of the Several Parts of the World; and Including Accounts of the Several Classes of Animalcules, Visible Only by the Assistance of Microscopes. London: Printed for Thomas Osborne, in Gray's-Inn, M.DCCLII [1752].
Available via Biodiversity Heritage Library @ https://www.biodiversitylibrary.org/page/56071325

Hill, John. "Dentalium." Urania, or, A Compleat View of the Heavens, Containing the Antient and Modern Astronomy, in Form of a Dictionary. London: T. Gardner, M.DCC.LIV [1754].
Available via Google Books @ https://www.google.com/books/edition/_/lzigAAAAMAAJ?hl=en
Available via Internet Archive @ https://archive.org/details/bub_gb_lzigAAAAMAAJ/page/n185/mode/1up

Hill, John. "The Shell Fish Series 1." Plate 7, opposite page 139. An History of Animals: Containing Descriptions of the Birds, Beasts, Fishes, and Insects, of the Several Parts of the World; and Including Accounts of the Several Classes of Animalcules, Visible Only by the Assistance of Microscopes. London: Printed for Thomas Osborne, in Gray's-Inn, M.DCCLII [1752].
Available via Biodiversity Heritage Library @ https://www.biodiversitylibrary.org/page/56071344

Hill, John. Urania, or, A Compleat View of the Heavens, Containing the Antient and Modern Astronomy, in Form of a Dictionary. London: T. Gardner, M.DCC.LIV [1754].
Available via Google Books @ https://www.google.com/books/edition/_/lzigAAAAMAAJ?hl=en
Available via Internet Archive @ https://archive.org/details/bub_gb_lzigAAAAMAAJ/

Hill, John, M.D. [Urania]. A New Astronomical Dictionary, or, A Compleat View of the Heavens Containing Antient and Modern Astronomy Illustrated with a Great Number of Figures. London: T. Gardner, MDCCLXVIII [1768].
Available via Internet Archive @ https://archive.org/details/bim_eighteenth-century_urania-a-new-astronom_hill-john-m-d-calli_1768/

Marriner, Derdriu. "English Naturalist John Hill Introduced 15 Constellations in 1754." Earth and Space News. Wednesday, Aug. 2, 2023.
Available @ https://earth-and-space-news.blogspot.com/2023/08/english-naturalist-john-hill-introduced.html

Marriner, Derdriu. "English Naturalist John Hill Named Bufo the Toad Constellation in 1754." Earth and Space News. Wednesday, Aug. 23, 2023.
Available @ https://earth-and-space-news.blogspot.com/2023/08/english-naturalist-john-hill-named-bufo.html

Marriner, Derdriu. "English Naturalist John Hill Named Eel Constellation Anguilla in 1754." Earth and Space News. Wednesday, Aug. 9, 2023.
Available @ https://earth-and-space-news.blogspot.com/2023/08/english-naturalist-john-hill-named-eel.html

Marriner, Derdriu. "English Naturalist John Hill Named Spider Constellation Aranea in 1754." Earth and Space News. Wednesday, Aug. 16, 2023.
Available @ https://earth-and-space-news.blogspot.com/2023/08/english-naturalist-john-hill-named.html

Sassarini, Iacopo. "4 Aquarii." The Sky Live > Constellations > Aquarius.
Available @ https://theskylive.com/sky/stars/4-aquarii-star

Sassarini, Iacopo. "11 Aquarii." The Sky Live > Constellations > Aquarius.
Available @ https://theskylive.com/sky/stars/11-aquarii-star

Sassarini, Iacopo. "12 Aquarii." The Sky Live > Constellations > Aquarius.
Available @ https://theskylive.com/sky/stars/12-aquarii-star

Sassarini, Iacopo. "15 Aquarii." The Sky Live > Constellations > Aquarius.
Available @ https://theskylive.com/sky/stars/15-aquarii-star

Sassarini, Iacopo. "16 Aquarii." The Sky Live > Constellations > Aquarius.
Available @ https://theskylive.com/sky/stars/16-aquarii-star

Sassarini, Iacopo. "21 Aquarii." The Sky Live > Constellations > Aquarius.
Available @ https://theskylive.com/sky/stars/21-aquarii-star

Sassarini, Iacopo. "69 Aquilae." The Sky Live > Constellations > Libra.
Available @ https://theskylive.com/sky/stars/69-aquilae-star