46 ADDRESS TO THE BRITISH ASSOCIATION, 1881. 



fathoms ; they have not been met with in the abysses 

 of the ocean. Here the bottom consists of exceedingly 

 fine clay, sometimes coloured red by oxide of iron, 

 sometimes chocolate by manganese oxide, and contain- 

 ing with Foraminifera occasionally large numbers of 

 siliceous Radiolaria. These strata seem to accumulate 

 with extreme slowness : this is inferred from the com- 

 parative abundance of whales' bones and fishes' teeth ; 

 and from the presence of minute spherical particles, 

 supposed by Mr. Murray to be of cosmic origin in 

 fact, to be the dust of meteorites, which in the course 

 of ages have fallen on the ocean. Such particles no 

 doubt occur over the whole surface of the earth, but on 

 land they soon oxidise, and in shallow water they are 

 covered up by other deposits. Another interesting 

 result of recent deep-sea explorations has been to show 

 that the depths of the ocean are no mere barren soli- 

 tudes, as was until recent years confidently believed, 

 but, on the contrary, present us many remarkable 

 forms of life. We have, however, as yet but thrown 

 here and there a ray of light down into the ocean 



abysses : 



Nor can so short a time sufficient be 



To fathom the vast depths of Nature's sea. 



In Astronomy, the discovery in 1845 of the planet 

 Neptune, made independently and almost simulta- 

 neously by Adams and by Le Verrier, was certainly 

 one of the very greatest triumphs of mathematical 

 genius. Of the minor planets four only were known in 

 1831, whilst the number now on the roll amounts to 

 220. Many astronomers believe in the existence of an 

 intra- mercurial planet or planets, but this is still an 



