66 SCIENCE IN SHORT CHAPTERS. 



has but one small moon that only displays her nearly full 

 face during a few nights of each month, the subject of 

 artificial light is only second in importance to those of 

 food and artificial heat, and every step that is made in the 

 improvement of our supplies of this primary necessary 

 must have a momentous influence on the physical comfort, 

 and also upon the intellectual and moral progress, of this 

 world's human inhabitants. 



If a cockney Eip Van Winkle were to revisit his old 

 haunts, the changes produced by the introduction of gas 

 would probably surprise him the most of all he would see. 

 He would be astonished to find respectable people, and 

 even unprotected females, going alone, unarmed and with- 

 out fear, at night, up the by-streets which in his days were 

 deemed so dangerous, and he would soon perceive that the 

 bright gaslights had done more than all the laws, the ma- 

 gistrates, and the police, to drive out those crimes which 

 can only flourish in darkness. The intimate connection 

 between physical light and moral and intellectual light 

 and progress is a subject well worthy of an exhaustive 

 treatise. 



We must, however, drop the general subject and come 

 down to our particular paraffin lamp. In the first place, 

 this is the cheapest light that has ever been invented 

 cheaper than any kind of oil lamp cheaper than the 

 cheapest and nastiest of candles, and, for domestic pur- 

 poses, cheaper than gas. For large warehouses, shops, 

 streets, public buildings, etc., it is not so cheap as gas 

 should be, but is considerably cheaper than gas actually is 

 at the price extorted by the despotism of commercial 

 monopoly. 



The reason why it is especially cheaper for domestic pur- 

 poses is, first, because the small consumer of gas pays a 

 higher price than the large consumer; and secondly, be- 

 cause a lamp can be placed on a table or wherever else its 

 light is required, and therefore a small lamp flame will do 

 the work of a much larger gas flame. We must remember 

 that the intensity of light varies inversely with the square 

 of the distance from the source of light; thus the amount 

 of light received by this page from a light at one foot dis- 



