INVENTION AND DISCOVERY. 555 



lion itself, of which it may be considered in many cases as forming a 

 part. 



If the invention, as is often the case, competes with or is intended 

 to supersede some older method, then there is a struggle for existence 

 between the two. This state of things has been well described by Mr. 

 Fletcher Moulton. The new invention, like a young sapling in a 

 dense forest, struggles to grow up to maturity, but the dense shade 

 of the older and higher trees robs it of the necessary light. If it could 

 only once grow as tall as the rest all would be easy, it would then get 

 its fair share of light and sunshine. Thus it often occurs in the his- 

 tory of inventions that the surroundings are not favorable when the 

 first attack is made, and that subsequently it is repeated by different 

 persons, and finally under different circumstances it may eventually 

 succeed and become established. 



We may take in illustration almost any of the great inventions of 

 undoubted utility of which we happen to have the full history — for in- 

 stance, of some of the great scientific discoveries, or some of the great 

 mechanical inventions, such as the steam-engine, the gas-engine, the 

 steamship, the locomotive, the motor-car or some of the great chemical 

 or metallurgical discoveries. Are not most, if not all, of these the 

 result of the long-continued labor of many persons, and has not the 

 financial side been, in most cases, a very important factor in securing 

 success ? 



The history of the steam-engine might be selected, but I prefer on 

 this occasion to take the internal-combustion engine, for two reasons — 

 firstly, because its history is a typical one; and secondly, because we 

 are to hear a paper by that able exponent and great inventor in the 

 domain of the gas-engine, Mr. Dugald Clark, describing not only the 

 history, but the engine in its present state of development and perfec- 

 tion, an engine which is able to convert the greatest percentage of heat 

 units in the fuel into mechanical work, excepting only, as far as we at 

 present know, the voltaic battery and living organisms. 



The first true internal-combustion engine was undoubtedly the can- 

 non, and the use in it of combustible powder for giving energy to the 

 shot is strictly analogous to the use of the explosive mixture of gas or 

 oil and air as at present in use in all internal-combustion engines ; thus 

 the first internal-combustion engine depended on the combination of 

 a chemical discovery and a mechanical invention, the invention of gun- 

 powder and the invention of the cannon. 



In 1680 Huygens proposed to use gunpowder for obtaining motive 

 power in an engine. Papin, in 1690, continued Huygens's experiments, 

 but without success. These two inventors, instead of following the 

 method of burning the powder under pressure, as in the cannon, 

 adopted, in ignorance of the thermodynamic laws, an erroneous course. 



