Beobachtung des Procyon als Doppelstern. Offprint from Mélanges mathématiques et astronomiques tirés du Bulletin de l’Académie impériale des sciences de Saint-Pétersbourg (dated 27 March/8 April 1873).

[St. Petersburg: 1874].

First edition, extremely rare offprint, of Struve’s ‘discovery’ of the faint companion to the star Procyon, which together form a binary system. This offprint is accompanied by two signed autograph letters from Struve to the Scottish amateur astronomer Robert Stirling Newall (1812-89), who at the time owned the largest refracting telescope in the world, asking Newall to confirm Struve’s observations. Neither Newall nor other contemporary astronomers were able to do so, however, and it was later shown that Struve’s observations were illusory, probably caused by a defect in his telescope lenses. Ironically, however, Struve was correct that Procyon is a binary system: the companion star was observed by the Lick Observatory in 1896. OCLC lists only one copy of this offprint (Hamburg).

Procyon is the brightest star in the constellation Canis Minor. Its name, meaning ‘before the dog’, derives from the fact that Procyon comes into the sky shortly before Sirius, the ‘dog star’. In 1844 Friedrich Wilhelm Bessel (1784-1846) noticed that both Sirius and Procyon exhibited irregularities in their proper motions which Bessel “ascribed to the presence of unseen companions of each of these stars and he was dramatically vindicated in 1862 (after his death) when the American telescope maker Alvan Clark detected the companion of Sirius while testing a new telescope. The nature of this companion was not understood until the twentieth century, but it turned out to be the prototype of a whole new class of stars – the white dwarfs. Confirmation of Bessel’s prediction about one star strengthened belief that he had also been right about the other, and many people began to look for a companion to Procyon. We now know that this star, too, is a white dwarf: it is a curious coincidence of constellation mythology that both dog stars should have similar companions. White dwarfs are very small and very faint. It is particularly difficult to see them with certainty when they are close to a bright star. The succeed in detecting the companion of Procyon, the would-be discoverer had to have access to a large telescope and should, by preference, be experienced in double-star observations. Naturally, Otto attempted this discovery and, in 1873, believed he had made it. He published his discovery in that year, complete with measurements of the companion’s relative position, and he published further measurements the following year” (Batten, Resolute and Undertaking Characters, p. 181).

The two enclosed letters from Struve show his concern to have his ‘discovery’ confirmed by another observer.


Pulkovo 19 March 1873

Dear Sir

This evening with an extraordinary transparent sky and excellent images, I thought I could see a small companion of Procyon at a distance of somewhat more than 10". I would be most happy if this discovery could be independently confirmed by your magnificent telescope and for this reason I abstain from communicating to you in what direction that object was. Pray look out for Procyon and let me know if and where you see that small object. It was so distinctly seen and measured this evening that I hardly can believe it was an optical illusion.

Since we left England we have nothing heard from you and yours. I hope you have received the letter I wrote you from Cambridge. We frequently talk of you and the friendly reception we have met with in your house, but even more frequently I have to report on the excellent performances of your grand telescope. Prof. Littrow, I am told, wants to get a similar instrument from Cooke. Will he succeed with the second as well as with yours?

Please convey my and Mrs. Struve's most cordial compliments to Mrs. Newall and believe me

Very truly your

Otto Struve

Have you succeeded to provide the refractor with a good micrometer, so that we may hope to get this year a series of good distances of Neptune's satelllites?


Pulkovo 28 April 1873

My dear Sir,

I have the pleasure to acknowledge the receipt of your two letters. With regard to Procyon I am sorry to say that what you have thought to be the newly discovered companion is a small star in 40" distance, repeatedly observed by me since 12 years and which does not participate in the proper motion of the principal star. The true companion, as I have seen it, is more than three times nearer to Procyon on the following side. With a tolerably good state of the atmosphere I have no doubt you will see it easily, but certainly the enormous brightness of the principal star as seen in your refractor might offer difficulties that perhaps I do not appreciate sufficiently. Probably you will see the companion more easily with a somewhat higher power. According to your diagrams I should think you have used a very low power. Otherwise you could hardly have seen in the same field Procyon and the succeeding close double star.

In the present spring Procyon is already too far advanced to the west to give any chance for a favourable observation. Therefore I might delay to the next winter the hope to get from you the confirmation of the discovery.

It is a pity your refractor is not yet provided with a good micrometer. Otherwise the interesting periodic Comet of Tempel rediscovered April 3 by Stephens at Marseille, would be an excellent object to prove its power. The comet is so faint that only the most powerful telescopes will be able to furnish satisfactory determinations of its position.

Pray present my and Mrs. Struve’s respectful compliments to Mrs Newall.

Very truly your

Otto Struve


Neither Newall nor other astronomers Struve contacted (among them the great Canadian-American astronomer Simon Newcomb) were able to verify his observations, and eventually “Otto withdrew his claim to have discovered the companion of Procyon … Despite Otto’s conviction that the fault did not lie in the telescope, the objective of the 15-inch formed a ghost image of every bright star, and Otto and his assistants had taken this image for the companion of Procyon they had expected to see. Even the apparent changes in position could be explained by somewhat different positions of the telescope in the different years that the “companion” had been observed … Procyon’s real companion was not discovered until 1896, when it was found by Schaeberle [with] the 36-inch refractor of the Lick Observatory. We now know that Otto’s observations did not fit at all the well-determined modern orbit of the system” (ibid., p. 184).

Winner of a Gold Medal of the Royal Astronomical Society and a member of the Russian Academy of Sciences, Struve (1819-1905) was a Russian astronomer who pioneered the study of double stars and contributed greatly to our modern understanding of astrophysics. Son of the Russian astronomer Friedrich Georg Wilhelm von Struve (1793-1864), he completed school education at the age of 15 and university education at the age of 20. During his time at the Imperial University of Dorpat, Struve helped his father catalogue the northern skies. Struve took on management of the Pulkovo Observatory from his father in 1858, became its Director in 1862, and remained so until his retirement in 1889. He is credited with discovering an estimated 500 double star systems along with detailed published measurements of their orbits. He completed the most accurate measurement of the earth’s curve, known as the Struve Geodetic Arc, categorized the rings of Saturn and discovered the second moon of Uranus. His sons, Ludwig and Hermann, and his grandson Otto, all became successful astronomers.

Newall (1812-1889) was a Scottish engineer and astronomer. He devised a machine for making wire ropes, and made substantial improvements in the construction of telegraph cables. The first successful cable, laid between Dover and Calais on 25 Sept. 1851, was made in his factory. Newall was a keen astronomer, and he commissioned Thomas Cooke to build a telescope for his private observatory at Ferndene, his Gateshead residence. For many years, this 25-inch refractor was the largest in the world. Newall was elected a fellow of the Royal Astronomical Society in 1864, of the Royal Society in 1875.

8vo (219 x 143 mm), pp. 21-28. Original plain blue wrappers, slight vertical creas from having been folded for postage, some minor spotting.

Item #4324

Price: $1,500.00

See all items in Astronomy, Relativity Theory
See all items by