THE ART OF THE ENGINEER, by Ken Baynes and Francis Pugh (The Overlook Press/Viking, $60). DaVinci's sketches--of those marvelous flying contraptions, pulleys and levers--mark the transition from flat, lifeless medieval art to the depth and perspective of the real world. With the coming of the Industrial Revolution, mechanical drawings developed even further from the speculative doodlings of genius into meticulous instructions for assembling gleaming turbines and gossamer-winged flying machines. The Art of the Engineer celebrates that draftsmanship in 234 intricate drawings that seek not just to depict the industrial process but to direct and control it. Here are the earliest Boulton and Watt specifications for their cumbersome steam engines, rust and ochre views of steam locomotives, and the illustrated dreams of the first fliers and auto manufacturers.

EARLY SCIENTIFIC INSTRUMENTS, by Nigel Hawkes (Abbeville, $29.95). "The true end of knowledge is not the pleasure of the mind but a line and race of inventions that may in some degree subdue and overcome the necessities and miseries of humanity." The sentiment thus expressed by Roger Bacon lives in the 73 instruments of scientific investigation examined here in close, colorful detail. They are the instruments that brought us understanding of the heavens, control of electricity, light in the darkness: among them are the 1767 microscope of J.B. Priestley, father of modern chemistry, and a crude early microphone made in 1878 by David Hughes. The full-page photographs are somewhat haphazardly arranged by the type or function of the instruments, but Hawkes carefully describes the function and history of each. For the tinkerer with some knowledge of the history of science, this book will provide many happy hours of revery.