Introducing Strickland’s Chart

Hugh Strickland, like most serious botanists and zoologists of his day, believed in special creation rather than evolution, but his work clarified the meaning of the resemblances expressed in Linnaean taxonomic groups. His vigorous opposition quashed the popular quinarian system, which had forced taxa into regular patterns. He insisted that analogies (now called homoplasies, the result of convergent evolution) should be ignored in classification.  Darwin built his theory on this concept of taxonomic affinity.

I travelled to England in May, 2012, to view the “Strickland chart.”  This remarkable document is a wall chart of the sort commonly made by 19th and early 20th century lecturers,  before the invention of slide projectors. (Such charts can be seen in use in Plate 22 in Morrell and Thackray’s history of the British Association for the Advancement of Science.) Strickland’s chart bears the title “Natural Affinities of the Class of Birds” and measures 88 by 207 cm. It belongs to the Strickland Archive in the University Museum of Zoology, in Cambridge, England. Its exhibition at Two Temple Place, London (January 31 to April 27, 2014) marks the end of 170 years of obscurity.

Hugh Strickland’s widow gave his bird collection to the University Museum of Zoology in 1867, and she gave his ornithological books in 1875, but the chart was likely not among these gifts, or it would have been used by Osbert Salvin, who prepared a catalogue of the bird specimens and regretted the lack of evidence of Strickland’s ideas of classification (1882, p. vi).  Probably it was among the papers given to the Museum in 1892 by a niece. In 1896 Alfred Newton (p. 104n) mentioned that he had seen the chart in the Museum, but then it seems to have been forgotten. In 1990 or thereabouts, pressed by the inquiries of historian Gordon McOuat, the Museum Archivist Ray Symonds found it, tightly rolled up.  At the urging of Dr. Adrian Friday, the Museum of Zoology commissioned its restoration (Rookmaaker pp. 9, 13, 319).

The chart was made in two stages, in 1843 and 1844.  Rookmaaker (2010) leaves the impression that the entire chart was made in 1843, which is the date given at the top of the chart. Voss’s book dates the chart to 1840, which is incorrect. 1840 was the date when he announced his plan, using one family, the Alcedinidae (kingfishers) as an example.  The top portion of the chart, titled “Natural Affinities of the Incessorial Order of Birds,” was displayed at the Cork meeting of the British Association for the Advancement of Science in 1843. Afterwards Strickland extended this chart by pasting on extra sheets of paper, on which he sketched the remaining kinds of birds in his three other orders (Rasores, Grallatores, and Natatores); only then did he add the wide blue lines that now prominently mark off his four orders.  He displayed this longer chart, renamed “Natural Affinities of the Class of Birds” at the BAAS meeting in York in 1844.

Strickland’s 1840 paper on Alcedinidae includes a “map” tracing the affinities of the genera to illustrate his method; although this resembles the later chart in some ways, there are also many differences. A.R.Wallace saw this map, admired it, and published his own diagrams of bird relationships based on that 1840 model (O’Hara 1988, 1991).

No portion of the chart was published in Strickland’s lifetime; after his death, his father-in-law William Jardine commisioned a two-volume collection of Strickland’s writings (published articles, and unpublished letters and diary). Presumably it was Jardine who commissioned a lithograph of the top portion of the chart (Jardine 1858). Jardine’s lithograph was republished by several historians (O’Hara, McOuat, and others). The first publication of an image of the chart was Voss (2007, plate 15; 2010 plate 3), which is in colour but only shows the 1843 portion, before restoration. Rookmaaker (p. 318) published an image of the whole restored chart, but in black and white. Few details, and almost no names, can be read on those published images.

Voss wrongly states that within Strickland’s small ovals are the names of species. In fact the lowest taxonomic rank Strickland used was the genus; the 1843 upper portion contains 490 generic names. In the 1844 lower portion, the lowest rank named are subfamilies.

During my brief visit, the chart’s location made photography difficult, but I took some snapshots with my digital camera, and Dr. Jamie Gundry devised a method of taking 12 high-resolution images so that I could study its details on my return to Toronto.

Working from these images, I engaged the assistance of  IHPST students Jennifer Coggon, undergraduate, Craig Knox, PhD candidate, and Ari Gross, PhD. Together we have produced two readings of Strickland’s chart: Names of Taxa, and Lines and Areas. The technique of making clear exactly what is on the chart is still a work in progress, and comments would be very welcome.