CATALOGUE OF THE MECHANICAL ENGINEERING COLLECTION. 33 



steam engine and having a one-stroke cycle. The engine was water 

 cooled. The electric spark was supplied by two Biinsen batteries 

 and an induction coil, the circuit being completed at the correct in- 

 tervals by contact pieces on an insulating disk on the crank shaft. 



On June 17, 1873, a United States patent was issued jointly to 

 L. C. Errani and R. Anders, of Belgium, for new improvements in 

 dynamic machines which the inventors called " a motor without gas." 

 The invention is of interest in that petroleum (presumably the 

 lighter oils) is stipulated and used for the propelling force. The 

 motor is, in general, similar to an ordinary steam engine, including a 

 cylinder, reciprocating piston, crank and flywheel, and valve gear 

 for operating through a cam a main valve connected with the cylin- 

 der. Shortly after Errani and Anders received their patent, a patent 

 was granted to J. Hock, of Vienna, Austria, Patent No. 151129, May 

 19, 1874, for improvements on the Errani and Anders motor, which 

 improvements resulted in the making of the first practically success- 

 ful oil engine. 



The gas and oil engines developed up to this time were of the non- 

 compression type. They were likewise heavy and awkward and gave 

 little power. But about the time that Hock obtained his patent, 

 G. B. Brayton, of Boston, Mass., obtained a patent, No. 151168, June 

 2, 1874, for an oil engine which worked on a constant pressure but 

 without any explosion. This appears to be the earliest compression 

 engine to use oil. 



Probably the greatest improvement made in the internal-combus- 

 tion engine was the compression of the explosive mixture in the 

 engine cylinder before ignition and the introduction of a practical 

 engine working on the four-cycle stroke. Both of these steps were 

 made by N. A. Otto, of Germany, and patented in the United States 

 August 14, 1877, Patent No. 194047. The compression of the explo- 

 sive was Otto's idea, but the four-cycle stroke, it is now conceded, was 

 proposed by A. Beau de Eochas, of France, in a treatise published in 

 1862, but it remained for Otto to develop it practically. Although 

 Otto developed and patented his ideas to apply to the gas engine, the 

 advantages were soon recognized and almost immediately applied to 

 the oil engine and are still so applied, further improvements being 

 mainly in the direction of higher compression. 



Shortly after the introduction of the Otto gas engine, a motor of 

 this type was brought out operated by an inflammable vapor pro- 

 duced by passing air on its way to the cylinder through the light oil 

 known as gasoline. A further supply of gasoline was subsequently 

 drawn into the cylinder to form the required explosive mixture w^hich 

 was then compressed and fired. The Spiel petroleum engine followed 

 and was the first Otto cycle motor which dispensed with an inde- 



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