EN
The examination o f pipe blocks in old organs plays an essential role in their conservation. The blocks constitute such an element of the instrument in which all changes in the condition of organs made over subsequent repairs become most apparent; they also reflect an artistry standard of an organ builder. Hence, their thorough examination is of utmost importance in establishing a proper conservation procedure. Until now the examination of blocks has been carried out by means o f an analysis of their outward surface, i.e. on the basis of a course o f visible channels, a likely course of invisible ones was determined. This method failed when the Organs Conservation Workshop had to face a conservation of a portable positive from Clarist Church at Nowy Sącz. In this situation it was decided to take X-ray photographies and on their basis to establish the course of channels. Still another advantage of-X-ray examinations is the fact that they make it possible to detect any changes and deposits formed as a result of repairs and also alterations introduced into the instrument, having thus an indirect effect upon a very important problem of determining the instrument’s condition afer conservation.