From the mid 19th century, gas engines were developed as feasible alternatives to steam engines, particularly for small power requirements. Their development was spurred by the establishment of gasworks and pipelines to deliver coal gas throughout many cities. The first successful gas engine was patented by Otto and Langen in 1866.
The Bisschop engine was developed in the 1870s as a very low power engine which did not suffer the noise and recoil of Otto and Langen's free piston engine. It is described as a non-compression engine since there is no compression of the air/gas mixture before its admission to the cylinder. The thermodynamic cycle is very similar to that of the Otto-Langen engine where the air/gas mixture is admitted early in the expansion stroke followed by ignition of the mixture, with exhaust occurring during the return of the piston. It was the adoption of a slider-crank mechanism that significantly reduced noise and vibration. The small power output of the engine required its rating to be in manpower rather than horsepower units, where one manpower is approximately 125 watts.
The engine was patented by Alexis de Bisschop of Paris in 1871, and the British patent rights were acquired by J E H Andrew & Co of Stockport, England in 1878. The engine proved modestly successful in spite of its relatively high gas consumption. It was more popular in England than in France, probably because gas was cheaper in England. Some 2000 engines were built in England before production ceased in 1894.
Buss, Sombart and Co of Magdeburg, Germany, also produced these engines from 1878 to 1886, and Mignon and Rouart of Paris was the principal French manufacturer. As Buss, Sombart was based in Otto's home market, it could not obtain a licence to make the more popular four-stroke engine during the term of Otto's 1876 four-stroke patent, and making the Bisschop was a viable alternative. Very few Bisschop engines, by any manufacturer, are still extant.
The engines were renowned for their simplicity and ease of repair and were considered the most successful of all so-called non-compression engines built. They were used to power a wide range of small machines and were particularly useful for intermittent operation. Although their gas consumption was relatively high, they were cheap to run when savings in wages were taken into account.
Debbie Rudder, Curator, and Noel Svensson, Powerhouse Volunteer, 2007
Lyle Cummins, 'Internal fire', Society of Automotive Engineers, Warrendale, USA, 1989, pp 116-121
Bryan Donkin, 'A text-book on gas oil and air engines', Charles Griffin, London, 1894, pp 113-117
Patrick Knight, 'The Bisschop engine', The Old Machinery Magazine, June-July 2001, pp22-24