Andrew Pritchard and Infusoria

Figure 1: Plaque to Andrew Pritchard, Newington Green Meeting House
Andrew Pritchard with microscope, 1840-1854. Science Museum Group
Notonecta or Boatfly together with magnified view of a 'mature animacule'. From Pritchard's Microscopic Cabinet, 1854.

Have you ever wondered what the ‘Infusoria’ are? Maybe you have also wondered how Andrew Pritchard, a man so beautifully commemorated in this plaque on the wall of the Meeting House, was and why he wrote of their History? (refer to Figure one)

The term itself – Infusoria – is now obsolete but its use is first dated back to 1763. Therefore, its history is firmly rooted in the early days of both microscopy and taxonomy, the discipline of naming, describing and classifying all living things. It is referred to as ‘an indiscriminate accumulation of microscopic animal and vegetable organisms, found in decomposing organic matter.’ Nowadays Infusoria are considered to have been organisms generally classified within the modern Protozoa. Originally, their production for the study was generated by gathering infusions of decaying organic material, and hence the name. (1)

Pritchard was born in Hackney in December 1804 and was the eldest son of John Pritchard and Ann Fleetwood. Following an education at St Saviour’s Grammar School, Southwark, he was apprenticed to his maternal cousin Cornelius Varley FRSA. (1781-1873) Varley himself was a renowned optical instrument maker and water-colourist. His artistic work, some examples of which are held by the Tate Gallery, (3) were closely connected to his interest in science and technology. From working on improvements to both the camera lucida and obscura; Varley went on to invent the graphic telescope, and in 1839 he co-founded the Royal Microscopical Society. (4)

Both Varley and Pritchard married sisters from the Straker family, a family with strong long-standing connections with the Sandemanian church. Varley himself, as well as other members of his family, where members of the Sandemanians from 1844 to 1847. Heavily involved as a leading congregant was Michael Faraday FRS (1791-1867) who was remembered through time for his contribution to the understanding of electricity and electromagnetic induction. From these close interconnections, it seems highly likely that Pritchard would have to meet Faraday, with perhaps each visiting the other’s place of worship in the questioning atmosphere of the non-conformists.

In 1834 Andrew Pritchard’s book, ‘The Natural History of Animalcule’  led to him being acknowledged as an expert in this field. He developed this reputation further with the publication of ‘A History of Infusoria: Living and Fossil’  in 1841. He received a glowing recommendation from a member of the Royal Institution, which was founded in 1799, and a fellow of the Royal Society of Edinburgh, for this work as an English naturalist and an acknowledged microscopist.

Pritchard went on to develop his talents as an accomplished microscopist. (5)  The invention of the microscope as such is dated to around the beginning of the 17th century and evolved out of the more competitive development of the telescope. Both instruments relied on the expertise of opticians and spectacle makers in the production of fine precision lenses, which is essential for the repeatable visualisation of a stable and reproducible image. (6) Pritchard introduced many improvements to the compound microscope of the day in an attempt to improve the refractive index and overcome chromatic aberrations allowing an enhancement of the veracity of the object image. He was the first to exploit jewelled lenses, credited with making a single lens from a diamond, and also working with lenses made from rubies and sapphires. (7)

From 1830 onwards, he collaborated with Dr Charles R Goring, variously described as an entomologist, zoologist and physician, but about whom surprisingly little information is otherwise readily available. Goring had already made his name in the world of microscopy by the introduction of what came to be termed ‘test objects’, namely a collection of calibrating objects with regular properties, such as insect wings, or arrays of cells,  which he used to test the power and resolution of his instruments.  (8) The two obviously had a close relationship, with Pritchard naming his first son after him. (9)

The language of the ‘Introduction’ to the first edition of Infusoria conveys a sense of his approach to the subject, his awe at this unexpected and unexplored world of the minute, underpinned by his religious conviction that God and nature were as one.

Interspersed throughout this world of nature, designed and formed by a gracious and All-wise Creator….. exists a world within a world, of beings so diminutive, as to have provoked man’s utmost ingenuity to bring them within the range of his perceptive powers. In the clearest waters, and also in the troubled, strongly acid, and salt fluids of the various zones of the earth; in springs, rivers, lakes and seas; in the internal moisture of living plants and animal bodies, and, probably, at times carried about in the vapour and dust of the whole atmosphere of the earth, exists a world, by the common senses of mankind unperceived, of very minute living beings, which have been called, for the past seventy years, Infusoria.  (2)

And he continues in this vein, marvelling at the astonishment available to ‘the quiet observer’, before embarking on the detailed formality of the scientific and technological description of his subjects.

Pritchard’s work The History of Infusoria, first published in 1841, rapidly became a standard work of reference and remained so for many years. His books are in the collections of some of the finest collections of the history of science in the world, and to the great delight of all, are now readily accessible online in all their glory (10):  a fitting modern equivalent to a plaque on the wall.


2A History of Infusoria, 1841


4See and

5see  for more examples of his work.

6 see  and and for further discussion of the development and milestones in microscopy.



9 (Sir) Andrew Goring Pritchard (1834-1928).


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