xxix.1 EXCEPTIONAL PHENOMENA. 661 



Scarcely more than a century ago it was held that fossils 

 were accidental productions of nature, mere forms into 

 which minerals had been shaped by no peculiar cause. 

 Voltaire appears not to have accepted such an explanation ; 

 but fearing that the occurrence of fossil fishes on the Alps 

 would support the Mosaic account of the deluge, he (Lid 

 not hesitate to attribute them to the remains of fishes 

 accidentally brought there by pilgrims. In archaeological 

 investigations the greatest caution is requisite in allowing 

 for secondary burials in ancient tombs and tumuli, for 

 imitations, forgeries, casual coincidences, disturbance by 

 subsequent races or by other archaeologists. In common 

 life extraordinary events will happen from time to time, 

 as when a shepherdess in Trance was astonished at an iron 

 chain falling out of the sky close to her, the fact being that 

 Gay-Lussac had thrown it out of his balloon, which was 

 passing over her head at the time. 



Novel and Unexplained Exceptions. 



When a law of nature appears to fail because some other 

 law has interfered with its action, two cases may present 

 themselves ; the interfering law may be a known one, or 

 it may have been previously undetected. In the first case, 

 which we have sufficiently considered in the preceding 

 section, we have nothing to do but calculate as exactly as 

 possible the amount of interference, and make allowance 

 for it ; the apparent failure of the law under examination 

 should then disappear. But in the second case the results 

 may be much more important. A phenomenon which 

 cannot be explained by any known laws may indicate the 

 interference of undiscovered natural forces. The ancients 

 could not help perceiving that the general tendency of 

 bodies downwards failed in the case of the loadstone, nor 

 would the doctrine of essential lightness explain the excep- 

 tion, since the substance drawn upwards by the loadstone 

 is a heavy metal. We now see that there was no breach in 

 the perfect generality of the law of gravity, but that a new 

 form of energy manifested itself in the loadstone for the first 

 time. 



Other sciences show us that laws of nature, rigorously 

 true and exact, may be developed by those who are 



