412 THE PRINCIPLES OF SCIENCE. [CHAP. 



extinct animals, or in any deposit not actually at present 

 in course of formation. Even Babbage accepted this con- 

 clusion as strongly confirmatory of the Mosaic accounts. 1 

 While the opinion was yet universally held, flint imple- 

 ments had been found disproving such a conclusion, and 

 overwhelming evidence of man's long-continued existence 

 has since been forthcoming. At the end of the last century, 

 when Herschel had searched the heavens with his powerful 

 telescopes, there seemed little probability that planets yet 

 remained unseen within the orbit of Jupiter. But on the 

 first day of this century such an opinion was overturned 

 by the discovery of Ceres, and more than a hundred other 

 small planets have since been added to the lists of the 

 planetary system. 



The discovery of the Eozoon Canadense in strata of 

 much greater age than any previously known to contain 

 organic remains, has given a shock to groundless opinions 

 concerning the origin of organic forms ; and the oceanic 

 dredging expeditions under Dr. Carpenter and Sir Wyville 

 Thomson have modified some opinions of geologists by 

 disclosing the continued existence of forms long supposed 

 to be extinct. These and many other cases which might 

 be quoted show the extremely unsafe character of negative 

 inductions. 



But it must not be supposed that negative arguments 

 are of no force and value. The earth's surface has been 

 sufficiently searched to render it highly improbable that 

 any terrestrial animals of the size of a camel remain to be 

 discovered. It is believed that no new large animal has 

 been encountered in the last eighteen or twenty centuries, 2 

 and the probability that if existent they would have been 

 seen, increases the probability that they do not exist. 

 We may with somewhat less confidence discredit the 

 existence of any large unrecognised fish, or sea animals, 

 such as the alleged sea-serpent. But, as we descend to 

 forms of smaller size negative evidence loses weight from 

 the less probability of our seeing smaller objects. Even 

 the strong induction in favour of the four- fold division of 

 the animal kingdom into Vertebrata, Aimulosa, Mollusca, 



1 Babbage, Ninth Bridgeivater Treatise, p. 67. 



1 Cuvier, Essay on the Theory of the Earth, translation, p. 61, &c. 



