After a quantitative analysis of the whole development of science and its specialized parts as well as technology, which shows that merely one half of scientific and technological results was created since 1850, the article reflects on tasks of historians in preparing an overview of that epoch. The paper follows important new technologies in 19th C. and suggests their connections with the results of earlier scientific research. It similarly analyzes the second half of 20th C. and concludes that technology creates specified epochs in which only a limited number of basic new inventions give the epoch its direction and essence. The first decennium of 21st C. will soon be over and there are only a few synthetic treatments of the development of science and technology in the 20th C. as a whole. The reason is the specialized education of researchers, who are not able to overcome their specialization and attempt more global historical syntheses. If it is difficult for a technician or scientist, it is even more so for a general historian, whose education in science and technology is relatively low. The large number and higher level of technical and scientific problems and the complicated subjects of scientific research also discourage synthetic work. The paper presents a quantitative analysis of the Current Bibliography of the journal ISIS, which shows that about 20 % of publications is devoted to the 20th C. but there are no works covering the whole development of science and technology during that period. Another problem comes from the difference between large and small countries. If the small country and its industry and research could be viewed like a great plant, enterprises of great and very developed countries are broadcast over the whole world. Therefore there is not only an internal need for a complete description of research and development in a country (it is possible to do better historical research with the development of one global broadcast enterprise). There would also be difficulties collecting the material to research. The paper also touches on the education of secondary school students, where is necessary to introduce history of science and technology into the history curriculum.