"In his book, the author Vladimir Vladimirovich Ryumin (1874-1937), a Russian engineer and a wonderful teacher, widely known as a popularizer of science and technology, tried to simplify the construction of devices and make it accessible to science lovers at minimal costs. (X-ray apparatus made of incandescent lamp, gas-discharge Geisler tubes without vacuum pump, self-made high-voltage Rumkorf coil, etc.), explaining the principle of their design and operation. Despite the inevitable obsolescence, science lovers will find interesting information."