88 THE POPULAR SCIENCE MONTHLY. 



of the size gives a spark ten times as strong as Franklin's ; or the 

 electrometers and galvanometers of Faraday with the mirror-galva- 

 nometers and electrometers of Sir William Thomson. Yet, at the 

 same time, let such an observer think of the possibilities of the next 

 fifty years, for the advance of science is not in a simple proportion to 

 the time, and the next fifty years will probably see a far greater ad- 

 vance than the one hundred years since the date of Franklin's electrical 

 work has seen. Is not the state of our imagination like that of the 

 shepherd-boy who lies upon his back, looking up at the stars of heaven, 

 and trying to imagine what is beyond the stars ? The only conclusion 

 is that there is something far more than we have ever beheld. Is not the 

 physicist of the future to have instruments delicate enough to measure 

 the heat equivalent of the red and the yellow, the blue and the violet 

 rays of energy? — instruments delicate enough to discover beats of 

 light as we now discover those of sound — an apparatus which will 

 measure the difference of electrical potential produced by the break- 

 ing up of composite grouping of molecules ? The photographer of to- 

 day speaks, in common language, of handicapping molecuits by mix- 

 ing gums with his bromide of silver, in order that their rate of vibra- 

 tion may be affected by the long waves of energy. Shall we not have 

 the means of obtaining the mechanical equivalent of such handicapped 

 vibrations ? Or, turning to practical science, let us reflect upon the 

 modern transmitter and the telephone, and contrast these instruments 

 with the rude, so-called lover's telephone, which consists of two disks 

 connected by a string or wire. What an almost immeasurable advance 

 we see here ! Would it not have been as difficult for Franklin to con- 

 ceive of the electrical transmission of speech as for the shepherd-boy 

 to conceive of other stars as far beyond the visible stars as the visible 

 stars are from the earth ? 



Yes, we have advanced ; but you will perceive that I have not an- 

 swered the question, which filled the mind of Franklin, and which fills 

 men's minds to day, " What is electricity ? " If I have succeeded in 

 being suggestive, and in starting trains of thought in your minds which 

 may enlighten us all upon this great question, I have indeed been for- 

 tunate. 



CHILIAN YOLCANOES, ACTIVE AKD EXTINCT. 



By KAKL OCHSENIUS. 



n^HE products of the extinct and the still active volcanoes of Chili, 

 -L of which Pissis enumerates not less than seventy, are of contem- 

 porary origin with the diluvial and alluvial strata of the country. Of 

 the gaseous emissions of their craters, it need only be mentioned that, 

 as in all_ American volcanoes, chlorine is weakly represented. The 



