210 A RISTO CRA CY AND E VOL UTION 



Book in cussion, and which no one proposes to take away, 

 or which no one is able to take away, or whose 

 number, if they were mentioned, would make all 

 discussion impossible, are passed over in silence, 

 for there is no need to mention them. Thus we 

 as we see all know that when a house is burnt to the ground 

 dfeatsstte tne causes of the phenomenon comprise the 

 cause of a fire, inflammable nature of timber, and indeed the 

 whole chemistry of combustion ; but if an insurance 

 office is disputing the owner's claim to compensation 

 on the ground that the owner set a light to it pur- 

 posely, whilst the owner maintains that the scullery- 

 maid set it alight by accident whilst reading in bed 

 a novel of Belgravian life, the only causes that will 

 be put forward by the litigants will, let us say, be 

 a candle alleged by the owner to have ignited the 

 scullery-maid's pillow-case accidentally, and on the 

 other hand a match which is alleged by the agent of 

 the insurance office to have been applied by the owner 

 to the drawing-room curtains intentionally. Or 

 again, let us take the case of a ship's chronometer, 

 or of the The reliability of a chronometer, any practical man 

 chronometer* w ^ te ^ us ^ we as ^ mm about the matter, depends 

 on the balance and the escapement. It is the perfect 

 " compensation " of the former and what is called the 

 " detachment " of the latter that differentiates the 

 chronometer from the ordinary lever watch ; and 

 these are rightly said to be the causes of the 

 chronometer's superiority as a time-keeper. But 

 a balance and escapement of themselves will not 

 keep time at all. They are useless without a main- 



