An exhibits entitled “La mesure du ciel - De la plaque photographique aux techniques spatiales” was held at the Observatoire de Paris in association with the Symposium 133, on the occasion of the centenary of the international enterprise which was named “Carte du Ciel” in 1887. Under the exception of some modern pieces such as maquettes of Ariane, of the Canada-France-Hawaii Telescope, of the Hipparcos Satellite, all other elements on display were from the resources of the Observatory. These case and some others, among the most recent ones, are analysed in view of studying the circumstances which allowed the objects and documents from the past to be still in our hands. The conditions through which they are still known and in existence are also reviewed. Based on such informations, some of the related problems are examined. In order to contribute to their solution, proposals could be made to the IAU Commission 41, in view of a study at the level of the International Astronomical Union. The author will be pleased to convey preliminary proposals to Commission 41.