Lot 1940s vintage technical booklets on servo system engineering

Lot of the vintage technical pamphlets on engineering servo systems. These are all written by Donald McDonald and published by Cook Research Laboratories (a division of Cook Electric Co). We're not sure of the exact vintage of these, but the address is listed as "Chicago 14" and we're guessing 1940s. They all have a name on the front covers.

There are "Multiple Mode Operation of Servomechanisms" (19 pages), "New Concepts in Servomechanism Design and Analysis" (22 pages) and "Nonlinear Techniques for Improving Servo Performance" (33 pages). These all include various graphs, charts and mathematical equations.

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Item No. n728442