134 Mayow 



lower end by the interposition of an island, as is seen 

 in the figure. For the air near the island, rotated from 

 b towards d^ when it has reached the island at <;, can 

 advance no further in that circle ; since therefore the 

 rotating air is pressed also by the external air adjacent 

 to it (and this, as has been already pointed out, is. 

 much condensed), it will necessarily be reflected 

 towards ^, where on meeting the air that has been 

 carried from h towards d^ it forces it outwards and 

 is turned round along with it towards/ And so, the 

 first vortex being interrupted, a new vortex, ^, / 

 emerges, in the centre of which the column of water 

 rises, as is shown in the same figure. But that new 

 vortex coming, at some height above the sea, say at 

 /, against the former ^vortex which is rotating with 

 the opposite motion, is by it, as being the more 

 powerful, gradually turned back, so that both 

 ultimately coincide at «, a. 



CHAPTER XII 



OF LIGHT AND COLOURS 



We have already treated of nitro-aerial spirit so far as 

 fire is kindled by it ; it remains for us to subjoin some 

 things about light, the peculiar and most wonderful 

 offspring of fire. With regard to rays of light, it can 

 scarcely be believed that certain effluvia of more 

 delicate flame, shot out from the luminous body^ 

 reach the beholder's eye. For who can imagine that 

 any fiery corpuscles can be brought, almost in a 

 moment, from the sun to the earth ? Much less is 

 it probable that fiery particles emanate from a small 



