Beautiful Comptometer or Adder in very good working order. USA, Circa 1920

This striking desktop machine is a comptometer, a device designed to add quantities in a mechanical way. It is a primitive calculator in real good condition which was made in Chicago circa 1920. The adding machine is well preserved and works fine, providing exact results. It has matt copper metal case and bone-colored and black keys. The case bears the black models name, Comptometer, embossed at the front and the back of the machine. The sides are embellished with black embossed decorative motives, much to the taste of the period. The comptometer is considered the first calculating machine with keys, so different from the first pinwheel calculators (arithmometers) which mounted levers. Patented by Dorr E. Felt in 1887 in the United States, it became a real bestseller: from its launching to the 1970s, millions of units were produced. The model that we can see in these images is Comptometer H, appearing in 1920 together with the J and the ST. These three machines bear the name at the front and the back and include a red release key.The calculator that we can see in the photos is quite remarkable for its great condition and working order. The metal case is very well preserved and so are the keys, being no one missing. By the keyboard there is a small metal plate with the serial number 208330. Over the keys there is another plate with the manufacturers name, Felt & Tarrant Mfg. Co Chicago, and a series of patent numbers.For its functionality and great charm, any collector of special machines will long to own this antique comptometer.