520 ADDITIONS. 



" The examples which Bacon gives of these ' Prerogatives' are very 

 curious, exhibiting, among some error and credulity, sound and clear 

 views. His leading example of the First Prerogative is the Rainbow, 

 of which the cause, as given by Aristotle, is tested by reference to ex- 

 periment with a skill which is, even to us now, truly admirable. The 

 examples of the Second Prerogative are three : — first, the art of mak- 

 ing an artificial sphere which shall move with the heavens by natural 

 influences, which Bacon trusts may be done, though astronomy herself 

 cannot do it — 'et tunc,' he says, 'thesaurum unius regis valeret hoc 

 instrumentum ;' — secondly, the art of prolonging life, which experiment 

 may teach, though medicine has no means of securing it except by 

 regimen ; 19 — thirdly, the art of making gold finer than fine gold, which 

 goes beyond the power of alchemy. The Third Prerogative of experi- 

 mental science, arts independent of the received sciences, is exempli- 

 fied in many curious examples, many of them whimsical traditions. 

 Thus it is said that the character of a people may be altered by alter- 

 ing the air. 20 Alexander, it seems, applied to Aristotle to know whether 

 he should exterminate certain nations which he had discovered, as be- 

 ing irreclaimably barbarous ; to which the philosopher replied, ' If you 

 can alter their air, permit them to live ; if not, put them to death.' In 

 this part, we find the suggestion that the fire-works made by children, 

 of saltpetre, might lead to the invention of a formidable military weapon. 



" It could not be expected that Roger Bacon, at a time when ex- 

 perimental science hardly existed, could give any precepts for the dis- 

 covery of truth by experiment. But nothing can be a better example 

 of the method of such investigation, than his inquiry concerning the 

 cause of the Rainbow. Neither Aristotle, nor Avicenna, nor Seneca, 

 he says, have given us any clear knowledge of this matter, but experi- 

 mental science can do so. Let the experimenter (experimentator) con- 

 sider the cases in which he finds the same colors, as the hexagonal 

 crystals from Ireland and India; by looking into these he will see col- 

 ors like those of the rainbow. Many think that this arises from some 



19 One of the ingredients of a preparation here mentioned, is the flesh of a drag- 

 on, which, it appears, is used as food by the Ethiopians. The mode of preparing 

 this food cannot fail to amuse the reader. " Where there are good flying dragons, 

 by the art which they possess, they draw them out of their dens, and have bridles 

 and saddles in readiness, and they ride upon them, and make them bound about 

 in the air in a violent manner, that the hardness and toughness of the flesh may 

 be reduced, as boars are hunted and bulls are baited before they are killed for eat- 

 ing."— Op. Maj. p. 470. 



'° Op. Maj. p. 473. 



