An Essay on Contagious Diseases: more particularly on the small-pox, measles, putrid, malignant, and pestilential fevers

In Short

This brief medical treatise, published in 1721, investigates the physical causes and bodily phenomena of dangerous and fatal communicable illnesses, particularly smallpox, measles, and malignant fevers. Drawing upon contemporary mechanical philosophy and microscopic observations, the author seeks to reduce complex diseases to simple principles by analyzing how airborne particles interact with the blood and animal economy. It has lasted as a historical artifact of early eighteenth-century medical thought, illustrating the transition toward applying mathematical and physical laws to biological pathology.

The Story

The inquiry opens with a general definition of contagious and epidemic diseases, noting how infectious particles generated in the air or borne from abroad afflict mankind with varying degrees of severity. The author lays down foundational propositions concerning the blood, utilizing microscopic insights from Leeuwenhoek and Malpighii to demonstrate how the magnitude and figure of blood particles change during infection. The treatise then examines how environmental factors—such as hot, scorching climates, stagnant waters, putrid exhalations, and famine—foster pestilential and malignant fevers, citing historical instances from Egypt, Grand Cairo, and classical antiquity.

Moving deeper into the animal economy, the text explains the mechanical alterations wrought by heat, moisture, and contagious particles. It details how the blood becomes depraved, forming larger molecules that obstruct capillary vessels and irritate the nervous system. The author investigates the process of putrefaction and fermentation, describing how volatile saline and oleaginous particles are released into the atmosphere and subsequently admitted into the body. While the skin is permeable, the lungs are identified as the primary site of infection due to the vast surface area of the pulmonary vesicles and the immense atmospheric pressure they sustain during respiration.

As the poisonous effluvia mingle with the blood, they coagulate its gross parts while volatilizing its subtler components, producing a cascade of distressing symptoms. The text systematically traces these manifestations, beginning with yawning, stretching, lassitude, coldness, shivering, and a low, quick pulse, before proceeding to more severe indications such as diarrhoea, inward heat, watching, delirium, trembling, and headaches. The progression reaches its physical peak in the formation of carbuncles, buboes, purple spots, and hemorrhages, which signify the complete breakdown of the vascular and animal economy.

The argument concludes by applying these mechanical principles to the eruption of pustules in smallpox and measles, explaining why certain parts of the body show symptoms sooner than others and why individuals who survive are rarely seized a second time. Finally, the text explores natural interventions, observing how hard frosts, strong northerly winds, or the rising of the Nile alter the disposition of the air and check the fury of contagious diseases, restoring a milder state to the afflicted populace.

How It Unfolds

• The foundational mechanics — The treatise begins by establishing physical propositions about the blood, demonstrating through microscopic observation how the size and shape of its constituent globules change to obstruct ultimate vessels.
• The environmental origins — The inquiry expands to external causes, analyzing how hot climates, stagnant waters, decaying matter, and famine generate putrid exhalations that foster malignant fevers.
• The physiological disruption — The text examines how environmental heat and contagious particles alter the animal economy, rarefying juices, relaxing fibers, and producing fevers through internal fermentation.
• The pulmonary pathway — The argument focuses heavily on respiration, calculating the atmospheric pressure on the internal surface of the lungs to prove that the primary mode of contagion occurs via the pulmonary vesicles.
• The symptom progression — A detailed sequence of bodily distress is mapped out, tracking the progression from early lassitude, shivering, and pulse irregularities to severe delirium, carbuncles, and hemorrhages.
• The resolution of crisis — The exposition concludes by explaining the mechanics of pustular eruptions in smallpox and detailing how environmental shifts like cold winds or rising rivers ultimately bridle the fury of epidemics.

The People

As a medical and philosophical essay rather than a narrative work of fiction, the book does not feature traditional characters with personal arcs. Instead, its central figures are scientific concepts, physiological systems, and historical observers whose findings anchor the argument.

The human body functions as the primary arena of the text, acting as a complex hydraulic and mechanical vessel whose fluids, fibers, heart, and capillary canals strive against invading forces. The blood is treated almost as an active participant, susceptible to coagulation, fermentation, and drastic textural degradation when confronted with hostile agents.

The author, Clifton Wintringham, serves as the guiding intelligence, attempting to bring order and intelligibility to terrifying maladies. Standing in his way are both the inherent obscurity of microscopic pathology and the entrenched medical dogmas of predecessors who dismissed these inquiries as too obvious to explain.

Historical observers and natural philosophers—such as Leeuwenhoek, Malpighii, Thucydides, Boyle, Newton, and Sydenham—appear throughout the text as authorities whose empirical observations and experiments support the author's mechanical deductions. None of these figures change personally, but through their collective contributions, the reader's understanding of disease shifts from mysterious terror to mechanical comprehension.

In Its Own Voice

The Design of this small Treatise being to deduce the Causes, and explain the Phoenomena of some of the most Fatal Diseases which afflict Mankind, can stand in Need of no Excuse...

The author states the straightforward purpose of his work in the preface.

The Magnitude of the Particles of the Blood must be increased either by the Union of a greater Number of them than in a Natural State; Or by the Alteration of their Figure, by which their Surfaces become larger than before.

The core mechanical proposition regarding how infections alter bodily fluids is laid out as a formal demonstration.

The Contagious Particles being admitted into the Blood, do there coagulate its Parts, and form Moleculæ of a larger Size than ordinary.

The central mechanism of contagion is concisely defined through the formation of obstructing molecules.

What It's Really About

The book is fundamentally an exercise in applying the mechanical philosophy of the seventeenth and eighteenth centuries to biological medicine. It wrestles with the underlying question of how invisible environmental agents physically alter human physiology, seeking to replace ancient or mystical notions of pestilence with rigorous physical explanations based on particle size, shape, momentum, and fluid dynamics. Wintringham's argument is that diseases like smallpox and the plague are not random curses, but orderly, mathematically comprehensible disruptions of the animal economy governed by the same mechanical laws that rule the inanimate world.

Why Read It Today

Readers with a deep fascination for the history of science and medicine will find this work genuinely absorbing. It offers a rare window into how early eighteenth-century thinkers conceptualized contagion before the discovery of bacteria and viruses, substituting corpuscles and hydraulics for microbiology. Reading it feels like stepping directly into a quiet, candlelit study in York in 1721, listening to a diligent physician painstakingly calculate the atmospheric pressure on lung vesicles using geometry and hydrostatics.

However, modern readers must be prepared for significant difficulties. The prose relies heavily on dense, archaic medical terminology, elaborate mechanical proofs, and period spelling conventions that can slow down comprehension. Furthermore, its medical theories are entirely obsolete, reflecting pre-germ-theory misconceptions about air, putrefaction, and bodily humors. Those who love patient historical craftsmanship and intellectual archaeology will appreciate its disciplined clarity, while casual readers may find its dry, mathematical approach to human suffering distant and arduous.