64 THE POPULAR SCIENCE MONTHLY. 



that it is combustible and evolves a large amount of beat in burning, 

 and tbat this heat can be set free at any time and be readily converted 

 into mechanical, chemical, electrical, and other forms of power. As 

 an illustration of the great amount of energy contained in coal, it is 

 well known to scientific men that each piece of it contains sufficient 

 stored-up power to lift its own weight twenty-three hundred miles in 

 height, or twenty-three hundred times its own weight a mile high. 

 The only other common natural substances to be compared with it in 

 this respect are wood and petroleum, and our stores of these are very 

 small. It is by the expenditure of the energy contained in coal that 

 comparatively valueless iron-ore is converted into valuable iron. 



It has not been by the mere existence of large quantities of coal in 

 this country, nor entirely by the sale of coal to foreign nations, that 

 so much of our wealth has been obtained, but largely by the circum- 

 stance that we were the first nation to apply coal to industrial purposes 

 on a large scale and in a great variety of ways. Other nations also 

 possessing coal, perceiving the great success of this method, followed 

 our example, have overtaken us, and have now rendered it increas- 

 ingly difficult year by year for us to maintain our position as manu- 

 facturers. 



As also large quantities of coal, petroleum, and inflammable gas 

 are continually being discovered and utilized in other countries, and 

 it is known that the United States of America alone contain nearly 

 forty times as much coal as our entire stock, the time can not be very 

 far distant when our chances of maintaining even our present position 

 among nations by means of our coal will be considerably less than at 

 present. It would be wise, therefore, boldly to face this serious pros- 

 pect, and consider by what means our national prosperity can be main- 

 tained as our coal diminishes in quantity and increases in price, 

 especially as our population is continually increasing and has to pur- 

 chase greater supplies of foreign food. 



There does exist another and inexhaustible source of wealth and 

 progress, viz., new knowledge obtainable by means of scientific re- 

 search. It is upon such knowledge, gained by experiments made to 

 examine natural forces and substances, that we must sooner or later 

 depend as a fundamental source of national prosperity. As fast as 

 this knowledge is evolved by discoverers, it is applied in more imme- 

 diately practical forms by numerous inventors, and then manufactur- 

 ers and men of business use those practical realities in the production 

 of wealth. This has been the order of events in the past and will be 

 in the future ; this was the way in which we got wealth out of coal. 

 Persons of narrow views on the subject will consider the above propo- 

 sition vague and unpractical ; but this order of things is a great fact 

 and unavoidable. We are the servants of Nature, and have no choice 

 in the matter ; we might as well hope to live without food as expect 

 to advance in civilization without the aid of new knowledge. 



