Descriptive Geometry | A. T. Chahly

Translated from the Russian by A. E. Tchernukhin and Th. Botting

Descriptive Geometry and Engineering Drawing are among the first engineering subjects taught at institutions of higher education. These subjects are essential if the students are to obtain a fundamental knowledge of the design and construction of machines and mechanisms.

Descriptive geometry, as a specific field of knowledge, like many others, arose and developed as a direct result of man’s creative labour.

The remains of fortresses, palaces and other structures found in India, Egypt, Greece, and other countries where there existed ancient culture, show that they were built in accordance with representations resembling modern drawings and conforming to the laws developed by descriptive geometry. A statue discovered during the excavations of ancient Babylon shows a man holding on his knees a slab with a structural drawing on it. The representations of plans and parts of building have also been found on the walls of Egyptian pyramids.

In our times Russian scientists and engineers have played an important role in the development of descriptive geometry and engineering drawing. Descriptive geometry in Russia was taught as early as 1810 in the St. Petersburg Institute of the Road Engineering Corps, now called the Leningrad Institute of Transport Engineering. Russian scientists have written a number of books on descriptive geometry, including such comprehensive courses as Fundamentals of Descriptive Geometry by Prof. I. A. Sevostya-nov, Descriptive Geometry by Prof. P. A. Galaktionov, as well as the textbooks A Course of Descriptive Geometry, On Curved Lines and Curved Surfaces, Manual of Engineering Drawing by Prof. A. C. Reder, the books Complete Course of Descriptive Geometry and Course of Linear Perspective Drawing by Prof. N. N. Makarov. Many other books were written by various authors during the first half of the 19th century.

The Soviet period in the history of methods of representation is marked, above all, by broad research work, better organization and improvements in the methods of teaching descriptive geometry, drawing and technical sketching in technical colleges and institutes.

Soviet scientists working in this field have contributed important theoretical works on diverse aspects of descriptive geometry. One such example is the work carried out on what are known as conditional representations by Prof. N. P. Chetveroukhin, which has led to the establishment of an entirely new branch of descriptive geometry. Others are the work on the problem of the precision of graphical constructions by Prof. D. I. Kargin, on the use of axonometric projections in architectural drawings by Prof. A. I. Viksel, on the use of methods of descriptive geometry in physical and chemical research by Academician N. S. Kournakov, Prof. V. N. Forma-kovsky and Prof. A. E. Anosov and, in mechanics, the work of the lecturers G. A. Ananov, E. A. Radov and many others.

Scientists who will work in the field of descriptive geometry are being trained at many institutes of the Soviet Union, in Moscow, Leningrad, Kiev, Tbilisi and other cities, where special departments of descriptive geometry and engineering graphics have been organized.

The geometrical properties of objects are usually studied with the help of their representations or drawings. By means of drawings the form of objects may be shown, the dimensions and relative positions of their various geometrical elements may be determined.

Descriptive geometry is devoted to the exposition of the theory and practice required for the solution of problems involving space distances and relationships and the techniques of constructing representations on a plane.

The fundamental objectives of descriptive geometry are:

1. The study of methods of constructing drawings of objects or

projects.

2. The study of techniques for determining the forms and

dimensions of objects with the help of drawings, i. e., the reading of drawings.

3. The study of the methods of solving problems involving forms in space by means of plane-geometry drawings.

Descriptive geometry is the theoretical foundation of engineer­ ing drawing which, in turn, is the preparatory graphical course required for studying all general engineering and special subjects.

Descriptive geometry develops the capacity for imagining objects in space which is essential for reading drawings.

Every engineer must have a good knowledge of the techniques used to represent objects by drawings. He must, so to say, be able to think in three dimensions. Creative engineering without this ability is quite impossible.

In this book descriptive geometry is dealt with step by step. Numerous examples are given to illustrate all theoretical aspects outlined and the methods of constructing projections.