THE LIGHT OF LAMPS AND CANDLES. 299 



the case of a steamer at sea, tossing and pitching about in 

 a storm." 



Besides these objections which Lawrence pointed out, 

 we may add that the process of preparing gas from coal, 

 or, as Lawrence called it, the work of " unpacking it," not 

 only involves the use of complicated machinery, but re- 

 quires skilled workmen to manage the machinery and to 

 conduct the process. And these men must devote, too, all 

 their time to the work, and must be well paid, so that it 

 is, on every account, much better to produce the gas for 

 illumination from some of the substances that can be used 

 in the form of candles or in lamps, though they cost more 

 at the outset. It is only when very large quantities of gas 

 are required, and in places, too, where there is ample room 

 for all the machinery and appointments, that it can be 

 profitably obtained from coal. 



Thus it can be manufactured advantageously on a great 

 scale for lighting cities and towns, and even for extensive 

 private establishments where there is plenty of space at 

 command for the necessary works; but for single dwell- 

 ings, or small establishments of every kind, if they are to 

 be lighted artificially at all, the gas must be brought in 

 packed, as Lawrence called it, in paraffine, or wax, or sper- 

 maceti, or tallow, or oil, or kerosene, or some other similar 

 hydrocarbon. 



"I never thought before," remarked John, when Law- 

 rence had made these explanations to him, " that, when 

 we were burning lamps or candles, we were really burning 

 gas." 



"Yes," replied Lawrence; "what is actually burnt in 

 both cases is essentially the same, only, in the case of a 

 candle or lamp, the gas is burned as fast as it is set free, 

 while in the case of regular gas-works it is kept from be- 

 ing burned for a time after it is set free, and is conveyed 



