The main directions and results of the activity of the famous talented scientist and teacher of the Lviv Geodetic School, professor A.L. Ostrovsky. On January 19, 2023, the Lviv geodetic community honored the 100th anniversary of the birth of Ostrovsky Apollinariy Lvovich – an outstanding scientist, professor, teacher known in Ukraine and abroad. Professor A. L. Ostrovsky published more than 200 scientific works, dozens of methodical developments in geodesy, topography; instrument science, he owns 11 copyright certificates and inventions. The birth of the Lviv School of Refraction is connected with the then professors of the Lviv Polytechnic Institute A. D. Motornyy and M. K. Mygal, and the first studies of the influence of atmospheric refraction on geodetic measurements were initiated by A. L. Ostrovsky To a large extent, the success in this work was brought about by the scientific activity of the employees of the branch research laboratory, which was managed by Apollinariy Lvovych in 1979–2006. This is how the Lviv Geodetic School of Refraction, known in the scientific world, was created. For many years, Prof. A. L. Ostrovsky headed the regional specialized Council for the defense of doctoral theses in geodesy, actively worked in the Educational and Methodological Council of the Ministry of Education and Culture of Ukraine, in the editorial boards of all scientific journals on geodesy and engineering geodesy published in Ukraine, and was the first editor-in-chief of the scientific journal Geodynamics. He was the scientific supervisor of almost 30 applicants who worked on candidate and doctoral theses. Among the pupils and students of Prof. A. L. Ostrovsky was an academician of the National Academy of Sciences of Ukraine Ya.S. Yatskiv, more than ten leading geodesist professors, many heads of geodetic enterprises and institutions in Ukraine and abroad. The fruitful scientific, pedagogical and professional activity of Prof. A. L. Ostrovsky brought him well-deserved respect in the scientific world and geodetic production, and was awarded high titles – Honored Worker of Science and Technology of Ukraine, “Honorary Surveyor of the USSR”, “Honorary Surveyor of Ukraine”, awarded with the Order of Merit III degree, and many honorary awards and medals. Professor A. L. Ostrovsky was a scholarship recipient of the President of Ukraine. Evidence of the unparalleled authority and deep respect on the part of the scientific geodetic community for A.L. Ostrovsky is the fact that he was elected as the head and honorary chairman of the organizing committee of the International Scientific and Technical Symposium “Geodetic Environmental Monitoring: GPS and GIS Technologies”, which has been held annually for many years worked in Alushta (Crimea).

The events of the emergence and development of higher geodetic education in Lviv are described in chronological order, starting from the establishment of the Department of Mathematics at the Lviv (Jesuit) Academy in 1744, where practical geometry was then taught, to the establishment of the Department of Geodesy and Spherical Astronomy at the Lviv Polytechnic in 1871 .and the opening of an astronomical observatory at it in 1880. The contribution to the development of education and science by the brightest representatives of the teaching staff of various nationalities is described, and the drawings of the textbooks prepared by them are given

The aim is to clarify the etymology of the terms “wall leveling mark” and “wall leveling benchmark” in the context of the historical sequence of the appearance of leveling networks in the Ukrainian lands to present the author’s view on these definitions in scientific reference and encyclopedic geodetic literature. To conduct a chronological study of the phenomenon of leveling wall signs of different structures and the corresponding technologies of binding to them in leveling networks, which were created in the Ukrainian lands during the XIX–XXI centuries. Pay attention to the fact that level marks and wall frames, which are valid (working) independent geodetic signs in leveling networks, due to long-term operation are carriers of important geodetic information. Method. To study the results of the analysis of historical sources, standards, reference, encyclopedic and scientific literature in the context of the analysis of the definitions of “level mark” and “wall benchmark” was used analysis of patterns of functioning of the relevant geodetic terminological units. Results. On the territory of Ukraine during the XIX–XXI centuries. Created a leveling (height) network [State Geodetic Network, experimental operation], which operates to this day. The functioning of the leveling (height) network is regulated by legislative acts and regulations. Thanks to the geo-portal of the DGM of Ukraine created by NDIGK, it is possible to obtain information about the preserved level signs. The peculiarity of the leveling (height) network is that it was created by different departments of different countries [Glushkov V.V., 2003] with different height systems and taking into account the access of Ukrainian lands to the Black Sea. All this led to the use of different designs of wall leveling signs and, accordingly, their interpretation, which is not sufficiently reflected in the geodetic reference and regulatory literature. Scientific novelty. The performed comprehensive analysis of information sources can serve as a basis for development of scientific and technical recommendations formonitoring of level signs ofDGMofUkraine and will allow to reveal weaknesses of their functioning which are caused by changes in vital activity of the city environment. The practical value of the work is to solve the problem of distinguishing the production characteristics of the wall leveling mark and wall leveling benchmark, which are fixed leveling signs in geodetic networks of thickening and leveling networks to develop technical developments for inspection and updating points II, leveling networks classes and geodetic networks of thickening in the context of monitoring of geodetic points of DGM of Ukraine and their corresponding representation in the scientific and reference geodetic literature.