482 THE POPULAR SCIENCE MONTHLY. 



150 B. a, Hero of Alexandria invented a little instrument called 

 an eolipile, which was driven by the agency of steam. To all ap- 

 pearances it was, and must ever remain, a useless thing ; and it 

 was not until the latter half of the eighteenth century that this 

 peculiar contrivance, after having passed through the hands of 

 De Gary, Porta, De Caus, Guericke, Savary, Papin, Newcomen, 

 Smeaton, and others, was transformed, by the inventive genius of 

 Watt, into a low-pressure engine. The history of this and other 

 inventions shows three classes of men to have wrought upon 

 them : First, there were the investigators, who were content with 

 only discovering the great laws and truths of Nature. Then there 

 were the teachers or historians, whose life-work was to treasure 

 and disseminate the truths obtained. As the virgins in the temple 

 of Yesta in ancient Rome kept the sacred fires burning, and would 

 not permit them to go out, so these men preserved the knowledge 

 thus obtained until the third class, known as the inventors, ap- 

 peared and made the application. 



How many, while admiring the objects attained by this third 

 class, have ever given a passing thought to the labors of the two 

 others, without which the last could never have accomplished 

 such magnificent results ? But are not the investigators of Na- 

 ture's laws as worthy of honor and as useful to humanity as are 

 the inventors ? Shall we compare Newton with the man who first 

 made a suction-pump ? Galileo, the discoverer of the properties of 

 the pendulum, with the manufacturer of a wooden clock ? Ar- 

 chimedes, the investigator into the buoyancy of liquids, with the 

 person who constructed the first dug-out ? Certainly not ! The 

 men who investigate the great truths of Nature, and the teachers 

 who disseminate those truths, and thus make invention possible, 

 are as true benefactors to humanity as are the inventors, though, 

 unfortunately, this latter class too often receive all the credit. 



In this connection we may also see that no knowledge is use- 

 less. The discoveries which at first seemed only ornamental are 

 frequently the forerunners of the most magnificent results. A 

 little plant peeps through the earth, buds, and throws out its 

 leaves, a thing pleasing to the eye. Presently it blossoms, the 

 flowers ripen, and the branches hang with luscious fruit. In like 

 manner many of the discoveries of the past, in their own day and 

 age apparently worthless, have in a subsequent generation been 

 found to be fraught with the greatest benefit to humanity. They 

 began as things curious and pleasing only to the lover of Nature, 

 but ripened into results of surpassing grandeur. The knowledge 

 which at one time seemed useless, at another has been found ex- 

 ceedingly serviceable ; and, since this has been true in the past, 

 shall it not also be true in the future ? If it took nineteen hun- 

 dred years from Hero's time until a Watt appeared to invent a 



