A widely circulated story holds that the word gadget was “invented” when Gaget, Gauthier & Cie, the company behind the repoussé construction of the Statue of Liberty (1886), made a small-scale version of the monument and named it after their firm; however this contradicts the evidence that the word was already used before in nautical circles, and the fact that it did not become popular, at least in the USA, until after World War I. Other sources cite a derivation from the French gâchette which has been applied to various pieces of a firing mechanism, or the French gagée, a small tool or accessory.
The October 1918 issue of Notes and Queries contains a multi-article entry on the word “gadget” (12 S. iv. 187). H. Tapley-Soper of The City Library, Exeter, writes:
A discussion arose at the Plymouth meeting of the Devonshire Association in 1916 when it was suggested that this word should be recorded in the list of local verbal provincialisms. Several members dissented from its inclusion on the ground that it is in common use throughout the country; and a naval officer who was present said that it has for years been a popular expression in the service for a tool or implement, the exact name of which is unknown or has for the moment been forgotten. I have also frequently heard it applied by motor-cycle friends to the collection of fitments to be seen on motor cycles. ‘His handle-bars are smothered in gadgets’ refers to such things as speedometers, mirrors, levers, badges, mascots, &c., attached to the steering handles. The ‘jigger’ or short-rest used in billiards is also often called a ‘gadget’; and the name has been applied by local platelayers to the ‘gauge’ used to test the accuracy of their work. In fact, to borrow from present-day Army slang, ‘gadget’ is applied to ‘any old thing.'
The usage of the term in military parlance extended beyond the navy. In the book “Above the Battle” by Vivian Drake, published in 1918 by D. Appleton & Co., of New York and London, being the memoirs of a pilot in the British Royal Flying Corps, there is the following passage: “Our ennui was occasionally relieved by new gadgets — “gadget” is the Flying Corps slang for invention! Some gadgets were good, some comic and some extraordinary