The 19th century Push-Pull type Tiemann Dynamometer was made of brass and steel by the American company of George Tiemann from New-York. This company has manufactured fine surgical instruments and other medical devices since 1826. Applying the force causes the two dial hands to move up together, but one “freezes” at the maximum force achieved, while the other follows the grip or pull up or down to show the current force strength. Measuring muscle strength with isometric dynamometers was used for many years in strongman championships.
(Source Image URL from gilai.com)