- Messier did his observing with a 100 mm (four inch) refracting telescope from Hôtel de Cluny (now the Musée national du Moyen Âge), in downtown Paris, France. The list he compiled contains only objects found in the area of the sky he could observe, from the north celestial pole to a declination of about −35.7°. They are not organized scientifically by object type, or even by location. The first version of Messier's catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45 objects being Messier’s. By 1780 the catalog had increased to 80 objects.
You can wander around the 110 objects in his catalog here: http://messier.seds.org/