 In 1891, Piot filed a patent application in the UK for a simple pop pop boat using a small boiler and two exhaust tubes.A 1975 article by Basil Harley mentions a similar boat seen in a French journal from 1880, indicating that this type of toy may have existed for many years prior to Piot's patent.In 1915, an American named Charles J. McHugh filed a patent application for the diaphragm type of engine, which was an improvement to Piot's design.