• Observations et dessin de la belle nébuleuse de la ceinture d'Androméde, la première qui fut découverte, et de deux petites nébuleuses, l'une au-dessus de la grande et le seconde au-dessous, vues dans une lunette qui renverse, comme le dessin, par C. Messier. Mémoires de la classe des sciences mathématiques et physiques de l'Institut National de France. Premier Semestre de 1807. P. 206-213 + plate.

Before the invention of the telescope in 1609, one didn't know that the Nebula, which we call Nebula of Cancer, which is seen to the naked eye, for the majority of eyes, like a nebula, and which is nothing but a cluster of small stars which are distinguished with telescopes. (I have determined them in 1785, 1790, and 1796, as well as those of the Pleiades). The beautiful and great Nebula in the girdle of Andromeda, singular by its form and its brightness, which one sees in a good sky with the naked eye in the form of a small whitish cloud, has been taken several times for a comet which started to appear, although [even when] seen with refractors, which has happend in my time at Calais to M. R**, who has announced it as a comet to the Academy of sciences, with a drawing of its position.

It is Simon Marius to whom is attributed the discovery with telescopes, of that beautiful Nebula in 1612; yet in a writing of Bouillaud, it is there said that it was remarked more than 600 years before him (1).

Several astronomers have observed since these times that Andromeda Nebula, and in particular that in the Sword of Orion, discovered by Huygensin 1656, (the most remarkable Nebulae in the sky, which have been observed as the first). The one and the other of them are suspected of variations in their shapes and equally to be subjects to disappear and reappear by a diminishing and augmentation of their light; M. Le Gentil has seen the Andromeda Nebula, round, then oval; and with a refractor of 3 feet focal length, he saw it, on January 7, 1758, in the form of two cones of light opposed at their bases, of which the two tips were distant about 50 minutes of arc, and the common base of the two luminous pyramides 20 minutes of arc. M. de Cassini said that its figure is a bit more triangular; (Élémens d'astronomie, page 78).

I say that the telescopes of more or less focal length, with more or less strong magnificaitons which one employs for the observations or for examining the Nebulae, produce different effects, and they reproduce them more or less dense or more or less obscure; it is surely the difference of these telescopes of more or less [focal] length which have been employed, and which have given the variations of the observed shapes, described and drawn of these two beautiful Nebulae.M. le Gentil has already remarked that he preferrred a refractor of three feet [focal] length over one of a larger length which he had employed, and recommends to employ refractors of equal length would make little efect for having more light, what agrees for the observation of the Nebulae for knowing their extension.

The various drawings which I have seen and which are published of the Orion Nebula, by Huygens, Picard, de Mairan, le Gentil, have determined me in 1773 to observe and draw with care and with the aid of an excellent achromatic refractor of three feet and a half [FL]; it is printed, Mem. Acad. for 1771, pl. VIII.

....

Note. The third comet of 1790 was situated, on May 2 in the morning on the parallel of the great Nebula of Andromeda, with which the comet was compared, and with the star Nu, of fourth magnitude of that constellation; reducing the observation I remember that I have committed an error in the position of the Nebula, reported in my printed Memoir of the Nebulae, volume of the acad., 1771. Here is that position rectified by the new observations for August 3, 1764. Read in my Memoir 7d 25' 56" instead of 7d 26' 32"; for the declination 39d 58' 11" instead of 39d 9' 32". For the small [nebula] discovered by M. Le Gentil, read 7d 24' 55" and 39d 33' 44". MM. [Monsieurs] Cassini and Méchain, who have compared the comet with me with the Nebula, found the same error; I have already reported it in the memoir of that comet, vol. of the acad. 1790, p. 322.

The first column, the numbers which are at the stars in the drawing; the second, their magnitudes; the third, their right ascensions and those of the three nebulae; the fourth, the differences of the right ascension of the center of the [Andromeda] Nebula and the stars; the fifth, the declinations; the sixth, the differences of the center [of M31] and the stars, and the seventh, if the stars are to the north or the south of the center of the [Andromeda] Nebula.

Nos. Magni   Right     Differ.   Northern   Differ.   
     -tude   Ascen.              Declin.
              1795

            d. m. s.   m. s.     d. m. s.   m. s.
 22    10    6 54 28   59 19 E   39 18 36   49 51 N
 21    10    6 56 58   56 49 E   39 18 36   49 51 N
 20    11    6 58 13   55 34 E   39 30 30   37 57 N
 19    10    6 58 43   55  4 E   39 33 35   34 52 N
S.N.  S.N.   7 18 39   35  8 E   40 32 26   24 19 S   Small Nebula. Messier.
 18     7    7 24 43   29  4 E   39  6 24   62  3 N
 17     9    7 27  9   26 37 E   40 35 42   27 15 S
 16     7    7 43 51    9 56 E   39 34  7   34 20 N
 15    10    7 50  2    3 45 E   39 49 36   18 51 N
 14     9    7 52  9    1 38 E   40 33 59   25 32 S
S.N.  S.N.   7 53 35    0 12 E   39 44 18   24  9 N   Small Nebula. Legentil.
G.N.  G.N.   7 53 47    0  0     40  8 27    0  0     Great Nebula, the center.
 13    10    8  1 24    7 37 W   39 53 13   15 14 N
 12    11    8  7 17   13 30 W   39 46 43   21 44 N
 11     9    8 12 54   19  7 W   40 26 34   18  7 S
 10     9    8 17 39   23 52 W   39 33 51   34 36 N
  9     8    8 22  9   28 22 W   39 33 38   34 49 N
  8     9    8 23 54   30  7 W   40 11 10    2 43 S
  7     9    8 37 15   43 28 W   40  3 52    4 35 N
  6     7    8 42 39   48 32 W   39 41 28   26 59 N
  5    10    8 43 39   49 52 W   40 11 18    2 51 S
  4     9    9  1 47   68  0 W   40 10 15    1 48 S
  3     9    9  7 17   73 30 W   40  9 41    1 14 S
  2     8    9 27  9   93 22 W   40  9 47    7 40 N
  1     7    9 30 39   96 52 W   39 57 41   10 46 N
 Nu     4    9 38 24  104 37 W   39 57 41   10 46 N

[The captions in this drawing read, from above: Mém. de l'Inst. Class Math. et Phys. 1.er Semestre, Pag. 213. (Mem. of the Inst. Class Math. and Phys. 1st Semester, pag. 231).
Graticule for 0, 15', 30', 45' 1d deviation from M31's center in RA and Dec.
ANDROMEDA NEBULA.
Directions are marked: N, N-W, S-W, S, S-E, N-E. Marked are the Meridian and the parallel to the Equator.
The stars are marked with the numbers given in the table above. The nebulae are marked as follows: M 31, G.N. (Grand Nébuleuse, Great Nebula), Simon Marius 1612 and 600 years before, beautiful at sight (with the unaided eye). M 32, P.N. (Petite Nébuleuse, Small Nebula), Le Gentil 1749, plus belle (more beautiful). M 110, P.N. (Petite Nébuleuse, Small Nebula), Messier 1773, plus foible (fainter).
Magnitudes of the Stars [symbols given, mag 4 to 11]; Ladder of Minutes of Arc [scale given].
Engraved by E. Collin, after a drawing by M. Messier. The Circle is the background of the Sky, which cuts the field (of view) of the refractor.]

Last Modification: February 28, 2005