Adverse comments by Dr Jeff Horn, Manhattan College, in a review published in Physics World (March 2004) of The Life and Science of Léon Foucault. The Man who Proved the Earth Rotates.


Let me begin with the most apparently objective, and therefore most perturbing, of Dr Horn's criticisms:

Numerous errors of historical fact, especially in the early chapters, also do not inspire confidence in [Tobin's] non-scientific judgments.

I immediately e-mailed Dr Horn who graciously consented to supply a list of the errors so that I can correct any further printings and post corrections on these web pages.

Here are the claimed errors of historical fact that Dr Horn has provided so far:

1. page 4. Estates-General to National Assembly then to the Constituent Assembly.
I had written 'the États généraux transformed itself into the Assemblée Nationale Constituante, or National Consititutional Assembly'.  Dr Horn is right that there was an intermediate short phase of 'National Assembly', but my wording does not imply that the transformation was direct. In a broad overview of the French Revolution, I believe it is justified to omit a formation that lasted for only some 22 days. Incidentally, I used the word 'Constitutional' quite deliberately feeling many readers would not be familiar with the technical term 'Constituent'.
2. page 4. The revolution was thought to have about 40,000 'victims'.
In the caption to Fig 1.3 I state 'the Revolution's twelve thousand or so victims'.  I saw both figures in the literature and must admit I cannot remember why I chose the lower one. Further investigation has revealed the complexities of ascribing a figure. Most writers appear to refer back to Greer's  The Incidence of the Terror during the French Revolution. A Statistical Interpretation (1935). Greer enumerates about 17,000 people condemned to death by revolutionary tribunals and jurisdictions (and possibly the 12,000 figure I quoted comes from a repeat of this figure wherein the 7 has been mistranscribed to a 2). However, there were also numerous summary executions and disease killed many prisoners. Greer estimates 35-40,000 deaths in total. Further, Greer's figures refer only to the period known as the Terror (1793 September--1974 July) and exclude e.g. casualties of war. Forty thousand is a figure that is frequently quoted in writings about the French Revolution, though usually without all these caveats.
There is a critique of Greer's work by Shapiro & Markoff  The Incidence of the Terror: Some Lessons for Quantitative History (Journal of Social History 9, 193-218 1975) which I have not yet been able to access. But provisionally I would propose changing  'Revolution's twelve' to  'Terror's forty'.
3,4. page 9. Dates.
Dates given on this page are:
1848 June - June days during Second Republic
1836 - Louis-Napoléon's 1st attempted uprising (Strasbourg)
1840 - Louis-Napoléon's 2nd attempted uprising (Boulogne)
three years before the coup d'état - Louis-Napoléon's election as Prince-President.
1851 December 2 (night preceeding) - coup d'état
a year later - restoration of the Empire
1870 - Sedan
1808 - Birth of Louis-Napoléon
1873 - Death of Louis-Napoléon
1840s - Louis-Napoléon's imprisonment at Ham
I have checked all these dates in Delorme's Les grandes dates du XIXème siècle (9th ed. 1985) and/or other reference books and find no error, let alone more than one.
5. page 9. Who says the 2nd Empire is an embarrassment? More so than the Restoration? The Third Republic? How so?
I had written  'The Second Empire is a considerable embarrassment in France even today.' This is is my evaluation and I stick by it. Besides the reasons given in my book, my evaluation is based on the way in which the Second Empire is generally ignored in France (look in the history section of any French bookshop). My wife adds subsiduary evidence from furniture, where the Second Empire style is considered the height of embarassingly vulgar taste!
I made no comment about the Restoration or Third Republic.
6. page 11. Brittany has always extended to Nantes. Even today.
I had written  '...Brittany, which in the nineteenth century extented further south than now.'  The Revolution abolished regions as administrative units, replacing them by départements,  so in an administrative sense Brittany did not exist in the 19th century, but of course it persisted informally. Twentieth-century reforms reinstated regions as administrative units, but Nantes and its départment  are placed in the Pays de la Loire  region, not Bretagne.  I live in Brittany half the year, and it is true that many people in Brittany feel that Nantes is still Breton; but when Dr Horn's objections arrived, I was in Grenoble: at lunch I asked my colleagues in which region Nantes was situated. Not one suggested Brittany.
The important point is that a reader who looks at a modern map of French regions will find Nantes outside Brittany and needs to understand that the boundaries have changed. My wording conveys this.
7. page 11. Brittany's principal port is, however, Cherbourg and more goods come in to Le Havre than Nantes for Brittany in the mid-19th century.
I had described Nantes as 'Brittany's principal port'  and the context makes it clear that this characterisation applies to the late 18th/early 19th centuries. I have not been able to check tonnages, but note that Cherbourg does not even figure in the tables given for mid-century cabotage  (coastal shipping) or number of registered ocean-going ships in Block's Statistique de la France (2nd ed., 1875),  whereas Nantes does figure, despite the fact that it declined as a port during the first half of the 19th century owing to silting and the abolition of the slave trade. But even if there was more Breton traffic through Cherbourg (sequestered at the end of the Cotentin penninsula),  Cherbourg is in Normandy! 'Principal port' is obviously an ambiguous concept without further definition, but within the context of my book I do not think that it is unreasonable to restrict the choice of a region's principal port to a port within that region.
8. page 11. The revolution was NOT sympathetic to the slave revolt...
Quite right; I boobed. I had written 'A slave revolt had erupted in 1791, to which the French Revolution was of course sympathetic; but the susequent decade was one of bloody turmoil, especially when Napoléon I tried to restore slavery on the island.'
Correction: change second phrase to 'which was followed by emancipation two years later;'
9. page 11. ...and the number of slaves was far less than 500,000.
I wrote `nearly half a million slaves.'  Well, 500,000 is the number given in Table I of McClellan's Colonialism and Science: Saint Domingue in the Old Regime (1992)  for 1789-90, which is the appropriate date for my text. McClellan seems to have studied the issue closely and describes his figure as 'relatively conservative.' In fact, in text and footnotes he mentions that other historians have estimated 600,000 or even 700,000 since the head-tax on slaves did not include children or persons over 45. In defence of Dr Horn, however, McClellan's Graph I shows that slave numbers were increasing rapidly, and Dr Horn only needs to be thinking of 1770 instead of 1790 for his remark to be justified.
Correction: change 'nearly' to 'some'.

Conclusion:  Of Dr Horn's 9 errors of historical fact I can only fully concede two; the rest are debatable or plain wrong. No book is without errors---especially one that is as full of facts as mine---, and I am very grateful to all readers who point out mistakes because it is only by continual sifting and winnowing that error is eliminated. But on the evidence that Dr Horn has presented, his charge of 'numerous errors' cannot be sustained---nor, I hope, the conclusion that he draws from it.

Let me add three corrections of my own:
page 7. Having now read Sarda's recent Les Arago: François et les autres (2002),  it would be fairer to describe Arago as 'staunchly democratic'  rather than 'staunchly republican'.
page 139. '1-2 a.m.'  should be '1-2 o'clock'.
page 234. 'in 1868 the Scottish physicist...'  should be 'in 1862-64 the Scottish physicist...'

Professional historians will, however, be troubled by [Tobin's] use of sources, particularly his willingness to take contemporary comments at face value.

One can always be more critical, but it should be noted that I devote almost three pages (xii, 279-80) to the difficulties of sources and their interpretation. This is a feature about which most biographers keep singularly quiet! Further, as a result of intercomparing sources whenever possible, and trying always to find independent confirmation of secondary sources, I expose the great unreliability of the writings of the 19th-century popularizer Louis Figuier, whose fantasies have polluted the tertiary literature on Foucault for a century and a half. As to the 'contemporary comments' there is often no evidence on which to assess their validity, and indeed I sometimes quote conflicting assessments, such concerning Foucault's measurement of the speed of light. I leave it to the reader to decide what s/he believes. For example, by the end of the book, the reader is unlikely to in any doubt but that the pronouncements of the ever-upbeat Abbé Moigno are to be treated cautiously.


The author frequently uses phrases like "Foucault must have felt..." or "we can sense that..." to fill in the gaps in his evidence.

Absolutely! I tried very careful to separate fact from speculation, especially when it concerns personal feelings where the emotional response to a given situation can vary so greatly from one person to another. As I say on p.280, in ascribing motives and feelings I frequently wondered whether I was writing about Foucault or myself.

Still, the lack of personal touches and intimate thoughts--in an era when most biographies are rife with them--is extraordinary. On the occasions where the links can be drawn (page 129), the narrative is greatly enriched.

I'm not sure whether the first sentence is a criticism or a compliment, but as Dr Horn notes earlier, the trouble is fragmentary documentation. Nevertheless, the book does contain extracts from most of Foucault's few surviving letters where we can read such intimate thoughts as he was willing to put to paper. Some intimate thoughts also come from his newspaper articles. It should be noted that the links that Dr Horn praises on page 129 are just as much speculations as the "Foucault must have felts..."


The major problem with this book is that the reader does not get a sense of the man behind the science that fascinates Tobin so deeply. We learn that Foucault was independent-minded, prickly, bad at mathematics, and emotionally and mentally fragile. He liked the company of women, enjoyed drinking coffee, "probably did not smoke", and made many more friends than enemies. But lurking behind these broad judgments and statements of fact, the essence of the individual does not emerge from this book.

There is much more in the book about Foucault's personality than this--his childhood hypochondria and early timidity, his intemperance and yearning for love as a young man, his later coldness as well as his exasperating calmness, his aesthetic appreciation, his attachment to rationality, his arrogance at his doctoral oral, his generally measured comments in print but his lack of understanding that his frankness could be hurtful, etc, etc. Another reviewer has found that my characterisation of Foucault is such that he 'springs to life'.  But I have to agree with Dr Horn that Foucault remains enigmatical with apparently conflicting traits such as his wry humour and his lack of amiability. If I were to meet Foucault, I am uncertain whether I would be charmed or irritated by him, and have even less idea of what his reaction would be to me.


Making us care about an individual and how his life exemplifies an era---while placing that individual's accomplishments in a wider context--are different missions that await another swing of the pendulum or perhaps a further spin of the gyroscope.

The many people I meet who are enthusiastic about Foucault are so because of his extraordinary technical ingenuity: if you are not captivated by this, you are unlikely to care about Foucault. As to putting Foucault's accomplishments in a wider context, I do endeavour to place his major discoveries in the context of the scientific times and of modern understanding, but would agree that if you want e.g. a measured assessment of his contribution to the development of the electric arc light or electrochemistry, you will not find it in my book, which is already 352 pages long. As Dr DeVorkin says in his foreword, it is becoming apparent that the intellectual origins of modern physics and astrophysics are more complex than hitherto acknowledged by historians; and in this light my biography of Foucault is but a piece of evidence for a much larger synthesis that will need to be made by someone more versed in the history of science and technology than myself.


Return to reviews of The Life and Science of Léon Foucault.


William Tobin.
Revised: 2005 February 14