Headington Hill, bellows and giddiness: Alveolar CO2 pressure, and (self-) experiments in respiratory physiology

In 1905, John Scott Haldane and Mabel FitzGerald set out to ‘ascertain the limits within which the alveolar CO2 pressure varies in different individuals’  – i.e. they set out to discover a baseline figure for the carbon dioxide (CO2) pressure in the lungs of healthy human beings – ‘as a knowledge of these limits is essential to a correct appreciation of pathological changes in the alveolar CO2 pressure’. Or to put it another way, the team needed to determine the normal range of alveolar pressure in healthy people before anybody could judge how diseases affected people’s lungs.

To obtain the data, Haldane and FitzGerald used a method and apparatus  which Haldane had introduced in 1898 for measuring the percentage of carbon dioxide in the air people breathed out, widely known as the Haldane Apparatus. These measurements allowed the team to calculate the CO2 concentration or ‘pressure’ in the actual alveoli, and to draw conclusions on the exchange of CO2 and O2 between the lung and the blood – the very foundation of respiratory physiology.

Colleagues, friends and family were amongst the volunteers examined in the first set of experiments conducted at the laboratory at  Haldane’s home in North Oxford, in March and April 1905. These results of these experiments were recorded by Mabel FitzGerald in one of the many notebooks which survive in her archive.

FitzGerald Notebook

A small black notebook (pictured here with some of FitzGerald’s general notes on air analysis) – looking rather inconspicuous, but giving remarkable insights into early experiments in respiratory physiology.

Many familiar names come up:  colleagues at the Oxford Physiology Department like Gustav Mann and Francis Gotch, L.P.F.G and C.P.F.G – FitzGerald’s sisters Laura and Catherine Purefoy FitzGerald – but also Haldane’s own children Jack (the then 12 1/2 years old, future scientist J.B.S. Haldane) and Naomi (7 1/2), as well as Gotch’s daughters(?) Veronica (11) and Audrey (12 3/4).

Gustav Mann

Results for Gustav Mann

Laura and Catherine FitzGerald

…FitzGerald’s sisters Laura and Catherine…

Naomi Haldane

…and Haldane’s daughter Naomi, who became the writer, activist and women’s rights campaigner Naomi Mitchinson.

Even Jack and Naomi Haldane’s friends and classmates, and other pupils from the nearby Oxford Preparatory School (now the Dragon School), served as ‘guinea pigs’ – apparently, the children found the experiments quite exciting (…or possibly just better than their maths and Latin lessons).

The results of the experiments on men, women, boys and girls were published later in 1905 – jointly by FitzGerald and Haldane, but with FitzGerald being first author – in the Journal of Physiology  as ‘The normal alveolar carbonic acid [carbon dioxide] pressure in man’.

Haldane was (in-)famous for his self-experiments anyway, vividly described in Martin Goodman’s excellent Haldane biography Suffer and Survive: the Extreme Life of Dr. J.S. Haldane, and Mabel FitzGerald seems to have been keen to join him, as the last paragraph of ‘The normal alveolar carbonic acid pressure in man’ states: ‘A further experiment was made by. M.P.F.G. [Mabel Purefoy FitzGerald] to test the after-effects of moderate muscular exertion…’ meaning a bicycle ride of nine miles in 53 minutes.  Or, as FitzGerald’s notebook meticulously records:


“After bicycling 53 minutes without stop. ca. 9 miles. twice up Headington Hill – 2nd time hard work”

For anyone not familiar with cycling in Oxford: Headington Hill IS hard work, even once. Mabel FitzGerald must have been in very good physical condition (…and/or very determined!) especially considering that as a lady in the very early 20th century, she was probably wearing a heavy, full-length skirt or dress with a rather uncomfortable corset – and I doubt ‘lady bicycles’ had gears in these days!

FitzGerald bike

Mabel FitzGerald with her bicycle at Shalstone Manor, her grandmother’s home in Buckinghamshire, 1896

However, to obtain reliable results, the experiments on the after-effect of physical exercise on alveolar CO2 pressure needed better controlled conditions than just fiercely pedalling around Oxford suburbs on a bicycle. Therefore, further self-experiments, conducted in July 1905, involved physical exertion under laboratory conditions – ‘working bellows’, a kind of early treadmill or stepper exercise to simulate cycling or climbing stairs, as well as controlled breathing:

MPFG bellows

27 July 1905: “After working bellows 13 minutes […] Breathing quickly and great tendency to take short breaths. […] Great difficulty in knowing when one was inspiring or expiring.”

31 July 1905: "Giddiness considerable"

31 July 1905: “Giddiness considerable”

Not least, FitzGerald recorded details of her diet with the CO2 measurements she took from herself, several times a day:

"small slice mutton - potato- cauliflower - 2 pan cakes - H2O"

Luncheon, 5 March 1905: “small slice mutton – potato – cauliflower – 2 pan cakes – H2O”

Her breakfast on the 5th March 1905 was ‘2 cups of coffee, 2 pieces toast and marmalade’ at 9 a.m., and the same the next day, but followed by ‘Beef Steak Pudding – Jam pudding’ for luncheon.

FitzGerald did not pursue the ‘alveolar CO2 pressure and diet’ question, but instead took the research that she and Haldane had started in 1905 into hospitals, looking at patient cases at the Oxford Radcliffe Infirmary and elsewhere to examine ‘The alveolar carbonic acid pressure in diseases of the blood and in diseases of the respiratory and circulatory systems’. The result of this work was published in Journal of Pathology and Bacteriology in 1910.

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