CATALOG OF THE MECHANICAL COLLECTIONS J 55 



DAIMLER COMPOUND GAS ENGINE, 1879 



U.S.N.M. no. 308697 ; original patent model ; transferred from the United States 

 Patent Office ; not illustrated. 



This model was submitted with the application for Patent no. 

 222467, issued to Gottlieb Daimler, of Deutz-on-Rhine, Germany, 

 December 9, 1879. 



This is the first compound or multiple-expansion internal combus- 

 tion engine patented in the United States. It was also the earliest 

 engine employing two cylinders operating independently on the 

 4-stroke cycle but connected to the same crankshaft and so timed that 

 a power stroke occurred once in every revolution of the shaft. 



The model shows two horizontal single-acting cylinders connected 

 to cranks at either end of the same crankshaft. The two cranks are 

 in the same plane. A third cylinder of large capacity is located 

 between these two and coimects to a crank 180° ahead of the other 

 two cranks and on the same shaft. The two smaller cylinders each 

 draw in a combustible charge, compress it, fire it, and perform their 

 strokes together, but the working stroke of one cylinder takes place 

 while the other cylinder is taking in its combustible charge. The 

 products of combustion expelled from these cylinders pass to the 

 third or low pressure cylinder and perform further work by expan- 

 sion therein. The low pressure piston performs its working stroke 

 during each instroke of the high pressure cylinders. The high-pres- 

 sure cylinders in construction and operation resemble the Otto Engine 

 of 1877 {q.v.). 



WITTIG AND HEES TWO-CYCLE GAS ENGINE, 1880 



U.S.N.M. no. 308707; original patent model; transferred from the United States 

 Patent Office ; not illustrated. 



This model was filed in 1879 with the application for U. S. Patent 

 no. 225778, issued to Wilhelm Wittig and Wilhelm Hees, of Hanover, 

 Germany, March 23, 1880. 



This is the first 2-cycle engine patented in the United States. It is 

 of that class of engines having two cylinders, between which the 

 operations of the Otto cycle are divided. One cylinder and piston 

 serve to draw in, compress the explosive charge, and deliver it to 

 the working cylinder so that in the working cylinder a power im- 

 pulse is obtained on every alternate stroke. This type of engine is 

 generally considered the invention of Dugald Clerk, of Glasgow, 

 who received British Patent no. 1089, March 14, 1881, and United 

 States Patent no. 249307, November 8, 1881, for a similar engine. 



The model, which is made principally of wood, is purely diagram- 

 matic and illustrates only the features of the engine that are covered 

 by the patent. It indicates two parallel cylinders, with pistons con- 



