Like almost all great inventions the gas engine is the product of many minds. It didn't suddenly happen, but has been gradually improved. In fact the modern motor is similar in many respects to some of the oldest types. It is an interesting fact that some of the engines made as far back as 1835 failed only because of the imperfect developments of some of the smaller details rather than the adoption of incorrect methods.

The exact date of the first gas motor is not definitely known. It is credited to Huyghens as far back as 1680. Huyghens proposed to use the explosive force of gunpowder as power. These experiments of Huyghens were without practical results. Papin in 1690 continued along this line; he proposed to explode a certain amount of powder in a closed cylinder. The explosion forced the air out of check valves, leaving in the cylinder a partial vacuum, that is, a pressure less than atmospheric.

The atmospheric pressure of the piston acted during the down stroke. The objections to this method were many. A pressure of 15 pounds was the maximum that could be reached. This necessitated a large and cumbersome cylinder. Secondly, it was impossible to produce in the working cylinder a perfect vacuum, hence the actual force available in doing work was the difference in pressure between 15 pounds and the partial vacuum in the cylinder. These objections were so great that the experiments of Papin were useless, as far as any real influence on the modern engine is concerned.

W. L. Wright in 1833 made a fairly practicable engine. It was double acting, that is, received an impulse per half revolution. The operation was similar to the steam engine. The mixture of air and gas was forced by separate jumps into the working cylinder, during only part of the power stroke. The charge was ignited by an open flame. This is the first engine on record where complete working drawings were made, though it is doubtful that the engine ever was actually made.

Up to 1837 no attempt was made to produce an engine of the compression type. William Barnet in 1835 describes an engine which comprest the charge prior to the firing. Here also the charge of gases was fired while the engine was crossing dead center, hence the force of explosion was utilized during the entire power stroke. This motor was not similar to the present gas engine, as the charge of gas and air was separately comprest, discharged into the working cylinder under pressure and ignited.

About this time the advantages of previous compression became prevalent. Lenoir in 1860 used an engine of the compression type, but he did not have a clear understanding of the nature of gaseous explosions. The supdden rise of pressure upon explosion and also almost equal drop, he tried to prevent by injecting steam to reduce, as he supposed, the too sudden pressure due to explosion and transform it into a more gradual impulse.

In 1867 Otto brought out a practical free piston engine and in 1876 he produced an engine of the compression type. This had the greatest efficiency of any engine yet made and had a sale of about 16,000.

Otto produced an engine better than. he knew, as he attributed the economy of his ignition to a slow ignition of the gases, whereas the real cause of efficiency was due to the compression used.

Up to 1885, the engines marketed were of the low speed type. The causes were several, but Daimler in his inventions struck at the root of the difficulty by using liquid fuel, introducing the now universally used poppet valves, and hot tube ignition is now supplanted by electric ignition. The increase of motor speed permitted much smaller designs for equal power.

Modern engines are built along the lines originally thought out by Daimler