142 CONVERSATIONS ON THE 



of life. I suppose that with some of the most 

 complicated machines, such for example as 

 the cylinder printing-press, one man could do 

 more by the help of a little oil than two, or even 

 three, could without it ; and that a small boy, 

 like one of you, could turn a piece of machin- 

 ery that was well oiled for half a day at a time, 

 whereas if the wheels and other parts that 

 rubbed against each other were dry, it would 

 tire a strong man in less than an hour." 



" And is there nothing else that would do 

 as well, Uncle Philip ?" 



" No, nothing ; grease or fat would, perhaps, 

 answer for large coarse machinery, but it 

 would clog up and stop the finer kinds, such 

 as watches and clocks, and a great many 

 other delicate contrivances that have been in- 

 vented for various purposes." 



"But, Uncle Philip, is that olive oil that 

 people burn in lamps ? It looks very different 

 from the sweet oil that we buy in bottles." 



" No, lamp oil is got from whales, and some 

 other kinds of large fish ; olive oil is too costly 

 to be used for burning. Whale oil may be 

 purified, and made to look almost as transpa 

 rent as olive oil ; and, indeed, the best lamp oi 

 is almost perfectly clear and colourless." 



