568 TRANSACTIONS OF THE 



vacuum, though comparatively impracticable, is but a means 

 whereby some other power is applied. 



Caloric is again rendered productive of motion, through its 

 ability to promote chemical change. The expansion of gunpow- 

 der, of carburetted hydrogen and oxygen, and of other explosive 

 mixtures, when applied to driving a piston, involves a grand 

 objection, the shock of the explosion. This incessant percussion 

 certainly, though perhaps gradually, destroys the machinery; thus 

 condemning such an appliance, for the defect is remediless. 



The expense of apparatus, the cost of repairs, the liability to 

 derangement, the friction of the piston, and the irregularity of 

 movement, are greatly increased; while the two motors, gas and 

 steam, though so far about equally expensive, are also equally 

 susceptible of increased economy in generation and use. 



The most important office of caloric, is its production and 

 expansion of the vapor of liquids. There is one grand objection 

 also, to the use of any vapor except that of water, viz : neces- 

 sity of perpetually supplying the waste fluid at a cost which com- 

 pared with that of water, at once decides in favor of the latter 

 element. 



If volatile fluids are adapted because less heat prepares them, 

 they should be abandoned, because this heat generates a propor- 

 tionably small force. No power is gained, but the agent itself is 

 gradually lost. 



Steam is, thus far, the most trustworthy, convenient, and eco- 

 nomical of the natural motors. Such direct comparison of quali- 

 ties most clearly illustrate its advantages over all others, and its 

 peculiar and wonderful adaptedness to the converting of force 

 into motion. 



It is evident, then, for three reasons, that caloric is the force, 

 and that steam is the agent, whereby locomotion will be accom- 

 plished for many years. 1st. Comparatively, its nature is better 

 known, audits economical production and management are enga- 

 ging the majority of talent and labor. 2d. Theory and practice 

 have proved it to be superior to any known power. 3d. History 

 and reason teach that a rival can attain to success only in accord- 

 ance with that universal law, gradual developeraent. 



The future improvements in steam locomotion, may be antici- 

 pated by reasoning. 1st. Upon the undeveloped nature of steam; 

 and 2d. Upon the principles elicited by past changes. Such 

 speculation may refer, 1st, to generation; and 2d, to use. 



Suppose a locomotive to be toiling up a grade, the wind is 



