454 THE POPULAR SCIENCE MONTHLY. 



signs of the times, that the civilized nations of Europe and America 

 are awakening, slowly but surely, to this truth. The civilized world 

 is learning, thank God, more and more of the importance of physical 

 science ; year by year, thank God, it is learning to live more and more 

 according to the laws of physical science, which are, as the great Lord 

 Bacon said of old, none other than " Vox Dei in rebus revelata " the 

 voice of God vevealed in facts ; and it is gaining, by so doing, year by 

 year, more and more of health and wealth ; of peaceful and comfortable, 

 even of graceful and elevating, means of life for fresh millions. 



If you want to know what the study of physical science has done 

 for man, look, as a single instance, at the science of sanitary reform ; the 

 science which does not merely go to cure disease, and shut the stable- 

 door after the horse is stolen, but tries to prevent disease ; and, thank 

 God, is succeeding beyond our highest expectations. Or look at 

 the actual fresh amount of employment, of subsistence, which science 

 has, during the last century, given to men, and judge for yourselves 

 whether the study of it be not one worthy of those who wish to 

 help themselves, and, in so doing, to help their fellow-men. Let me 

 quote to you a passage from an essay urging the institution of schools 

 of physical science for artisans, which says all which I wish to say 

 and more : 



" The discoveries of voltaic electricity, electro-magnetism, and mag- 

 netic electricity, by Volta, Oersted, and Faraday, led to the invention 

 of electric telegraphy by Wheatstone and others, and to the great 

 manufacturers of telegraph-cables and telegraph-wire, and of the ma- 

 terials required for them. The value of the cargo of the Great Eastern 

 alone in the present Bombay telegraph expedition is calculated at three 

 million pounds sterling. It also led to the employment of thousands 

 of operators to transmit the telegraphic messages, and to a great in- 

 crease of our commerce in nearly all its branches by the more rapid 

 means of communication. The discovery of voltaic electricity further 

 led to the invention of electro-plating, and to the employment of a 

 large number of persons in that business. The numerous experimental 

 researches on specific heat, latent heat, the tension of vapors, the prop- 

 erties of water, the mechanical effect of heat, etc., resulted in the de- 

 velopment of steam-engines and railways, and the almost endless em- 

 ployments depending upon their construction and use. About a quar- 

 ter of a million of persons are employed on railways alone in Great 

 Britain. The various original investigations on the chemical effects 

 of light led to the invention of photography, and have given employ- 

 ment to thousands of persons who practise that process, or manufacture 

 and prepare the various material and articles required in it. The dis- 

 covery of chlorine by Scheele led to the invention of the modern pro- 

 cesses of bleaching, and to various improvements in the dyeing of the 

 textile fabrics, and has given employment to a very large number of 

 our Lancashire operatives. The discovery of chlorine has also contrib* 



