François Félix Tisserand – Forgotten Genius of Celestial Mechanics (Review by The Observatory)
The following review was published within the February 2019 edition C and is replicated below in full with kind permission of the editors of The Observatory. We also give our thanks and appreciation to Professor Chapman for his time and support.
This is only a short book but it truly brings to life not only Felix Tisserand (1845-1896) himself but also the world of French astronomy in the late 19th Century. It is clearly and elegantly written, and packs a great deal of information into a total of 85 pages, including colour plates, appendices and diagrams. Janet Hyde & Neil Taylor provide a clear sense of time, place, and personality, and set this illustrious celestial mechanician, the true successor to Laplace, into his historical context. What comes over particularly strongly is Tisserand’s humorous, genial personality, plus his gifts as an inspiring teacher and fair-minded director of both the Toulouse and Paris Observatories. And what a contrast to the arrogant and high-handed Urbain Le Verrier who fell out with most people, yet with whom Tisserand found a way of working. The quotations from the travel diary of Charles Piazzi Smyth bring this contrast out clearly. A mathematical genius from schooldays in Burgundy, where his cooper father made barrels for the wine trade, Tisserand’s scientific career focussed upon celestial mechanics. As a young man he travelled on several astronomical expeditions, most notably to Japan with Jules Janssen to observe the 1874 Venus transit, and excelled in the making of meticulous observations.
He is perhaps chiefly remembered today for the Tisserand Criterion, and the identification of returning periodic comets from their measured orbital criteria. Hyde & Taylor conclude by posing the question of why this eminent man is not better known. They suggest three possible reasons. Firstly he was overshadowed by the reputation of the long-dead (1827) Laplace; yet Tisserand’s publications advanced celestial mechanics well beyond Laplace. Secondly he was a modest, un-pushy man. And thirdly ‘bad timing’ was a contributory factor, for by the time of Tisserand’s sudden death – probably from a stroke in his sleep – at the age of 51 physics was rapidly moving into new realms, beyond that of celestial mechanics, indeed into the New Physics realm of Einstein, Bohr, Lorentz, making celestial mechanics seem somewhat dated.
The main text requires no prior knowledge of astronomy to read and enjoy, but detailed technical appendices are provided especially on the Tisserand Criterion.
The book is well produced and illustrated, and the smiling bust of Tisserand at his birthplace, Nuits-Saint-Georges on the front cover gives one a sense of the man who will be encountered inside. ALLAN CHAPMAN
François Félix Tisserand – Forgotten Genius of Celestial Mechanics (Review by the Society for History of Astronomy)
An extract from Society for the History of Astronomy (SHA) Bulletin Issue 30, Autumn 2018 with courtesy of and acknowledgement to David Sellers and the SHA.
“…Despite Tisserand’s accomplishments he is almost unknown to English-speaking historians of astronomy. This short book, François Félix Tisserand – Forgotten Genius of Celestial Mechanics, by Janet Hyde and Neil Taylor is therefore especially welcome. It is clearly a labour of love. Co-author, Janet Hyde – showing simultaneously the recent neglect of Tisserand and his continuing relevance…
“…The book is somewhat episodic in its structure and layout but succeeds very well in giving an overview of its subject’s life and achievements. Hyde and Taylor also convey something of the endearing character of Tisserand.
“…The book includes 8 appendices, dealing with the Tisserand family tree , The Tisserand criterion, his mathematics and celestial mechanics (at a very simple level), along with photos of some places associated with his life.
“…In a eulogy, Joseph Bertrand (secretary of the Paris Academy of Sciences) claimed that the name of Félix Tisserand shone in the front rank alongside the famous names of d’Alembert, Clairaut, Lagrange and Laplace, Le Verrier and Delauney. If Hyde and Taylor’s small book helps to ensure that this assessment is born out amongst anglophone historians of astronomy, then it will have been worthwhile. DAVID SELLERS
The Limousin Asteroid Impact of the Triassic Rhaetian Age (Review by The Observatory)
The following review was published within the June 2018 edition The Observatory 138, 1263, 2018 and is replicated below in full with kind permission of the editors of The Observatory. We also give our thanks and appreciation to Professor Hughes for his time and support.
The Limousin Asteroid Impact of the Triassic Rhaetian Age, by Neil R. Taylor (Observatoire Solaire), 2017. Pp. 71, 21 × 15 cm. Price £ 6.99 (paperback; ISBN 978 1 9999 044 1 8).
Dinosaurs died out about 66 million years ago. I well remember the famous American astronomer Fred L. Whipple telling me he had thought of at least thirteen things that could have caused this disaster. However, since the 1981 pioneering work of Luis and Walter Alvarez that led to the discovery of an iridium-enriched layer at the geological C–P boundary, together with the 1991 discovery of a huge impact crater on the edge of the Yucatán Peninsular in Mexico, modern opinion has centred on the impact of a fifteen-kilometre-wide asteroid as the cause. This impact resulted in the extinction of 75% of Earth’s mammals, amphibians, and plants. Also the Cretaceous age ended and the Paleogene started.
But the death of the dinosaurs is only one of the many disasters that have befallen our planet. There was a Great Dying about 251 million years ago, and a similar mass extinction about 201 million years ago. The latter again coincided with a geological age change, this time the Triassic switching to the Jurassic. Astronomers, hopefully being economical with their hypotheses (and remembering Ockham’s Razor), turn to similar causes. An asteroid did it, or at least it contributed massively to contemporary plate-tectonic activity and associated volcanism. So there must be another huge crater somewhere. And in the book under review the town of Rochechouart in the Nouvelle-Aquitaine region of west-central France is the proposed location. The big problem is recognition. Craters in the Earth’s surface are being progressively erased as they age. After a mere 65 000 000 years the 180-km-diameter Chicxulub crater in Mexico was so hard to find that we did not stumble over it until 26 years ago. Just how difficult will it be to find a crater that is smaller and three times as old? It could be anywhere.
In this well-written, authoritative, and beautifully illustrated book Neil Taylor explains how what is left of the Rochechouart crater was discovered in 1969 by the French geologist Fançois Kraut. Geological maps together with Bouger maps of gravity anomalies indicate that the crater was about 50 km in diameter. Its impact nature was confirmed by the discovery of local deposits of shocked quartz, lithic breccias, and suevite. Detailed 40Ar/39Ar isotopic measurements indicate that the crater formed around 201 ± 2 million years ago.
This delightful book is a superb introduction to the effects of an asteroid impact with Earth. It also is a great encouragement to visit this picturesque region of our European neighbour. I can hardly resist the suggested joys of wandering around the Eglise Saint Sauveur in Rochechouart and picking out the examples of the distinctly reddish Montoume suevites, the bluish-grey Chassenon suevite, and the brownish-grey local breccias in the church walls, followed by a coffee and pâtisserie in the local café on Place de Dr Octave Marquet. DAVID W. HUGHES.