James Lequeux

Arago’s Legacy

The model of Arago’s statue, erected in Paris in 1893. The sculptor, Alexandre Joseph Oliva (1823–1880) is visible on the left. The statue was placed close to the Paris Observatory on a pedestal by Joannis. Only this pedestal survives, because the bronze statue was melted during the Second World War. Bibliotheque de l’Observatoire de Paris

Arago and the Paris Observatory

The large dome of the Paris Observatory, built by Henri Alphonse de Gisors (1796–1861) and the engineer Louis Travers in 1847. From Arago’s Astronomie populaire, author’s collection

The Promotion of Science and Technique

The Buddicom steam locomotive used on the Paris-Rouen line from 1843, external view and cut. From Delaunay (1850), author’s collection

The Velocity of Light

Rotating mirror and its mechanism built by Louis Breguet in 1844 for Arago. After a few modifications, it was used by Fizeau in 1850 for the comparison of the velocity of light in air and in water. Bibliotheque de l’Observatoire de Paris

The Nature of Light

Autographed Memoir of Fresnel with the approbation of Arago, for publication by Academy of sciences. Archives de l’Academie des sciences

Scientific Life in France at the Time of Arago

Arago presents the details of the photographic process of Daguerre at the public meeting of the Academy of Sciences and of the Academy of Fine Arts on 19 August 1839. Private collection.

The Birth of Electromagnetism

A primitive electric motor built by Froment, mid-nineteenth century. Three pairs of coils (a vertical one is barely visible under the axis) successively attract bars of iron located around the rotor. A commutator in front distributes the current to the coils so that the rotor and the attached flywheel turn in the desired direction. Bibliotheque de l’Observatoire de Paris

The Years of His Youth (1811–1845)

Urbain Jean-Joseph Le Verrier was born on 11 March 1811 in Saint-Lo (Manche). His father, Louis-Baptiste Le Verrier, was an estates manager, born in Carentan. His mother, Marie-Jeanne-Josephine-Paulie de Baudre, was born in Baudre. Carentan and Baudre are two communities close to Saint-Lo; the grandparents of Le Verrier were also born in the region. The house in which he was born (Fig. 1.1) was a quite modest bourgeois home, attesting to their limited means.

The Discovery of Neptune (1845–1846)

The discovery of Neptune has been the subject of an immense literature, for it was undeniably one of the major scientific events of the nineteenth century. It is well known that the effort to discover the perturbing planet responsible for the abnormal behavior of Uranus was carried out simultaneously in England and France, and that La Verrier was the first to announce the discovery, John Couch Adams having independently obtained similar results. From these events, interminable controversies followed, in which nationalism played a large role, and even today they are not totally extinguished.But at least it is now possible to look at these matters with cooler heads, and with relative neutrality.

The Second Reign (1873–1877)

The death of Delaunay plunged the Minister of Public Instruction into confusion. Who should replace him? None of the astronomers at the Observatory were eager to take on the responsibility. Finally, it was the president of the Republic, Adolphe Thiers, who decided the matter. Thiers had maintained contact with Le Verrier, and decided to bring him back. The latter was therefore nominated director on 13 February 1873, 6 months after the drowning of Delaunay. His family didn’t seem to be in a hurry to move back to the Observatory, fearing, no doubt, a cold reception there. Though several astronomers, including Wolf, had hoped for his return, Le Verrier never forgave them for having signed the infamous manifesto of 1870 which ended in his dismissal, and in the end Wolf and Le Verrier would no longer be friends.