ADDRESS. 25 



this is the case with some clays also. In that case the striking remark 

 of Linnaeus, that ' fossils are not the children but the parents of rocks,' 

 ■will have received remarkable confirmation. I should have thought it, 

 I confess, probable that these clays are, to a considerable extent, com- 

 posed of volcanic dust. 



It would appear that calcareous deposits resembling our chalk do not 

 occur at a greater depth than 3,000 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 containing with Foraminifera occasionally large 

 numbers of siliceous Radiolaria. These strata seem to accumulate with 

 extreme slowness : this is inferred from the comparative abundance of 

 whales' bones and fishes' teeth ; and from the presence of minute spherical 

 particles, supposed hy 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 solitudes, as was until recent years confidently believed, but, on 

 the contrary, present us many remarkable forms of life. We have, how- 

 ever, 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 simultaneously 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 

 open question. The Solar System has also been enriched by the dis- 

 covery of an inner ring to Saturn, of satellites to Mars, and of additional 

 satellites to Saturn, Uranus, and Neptune. 



The most unexpected progress, however, in our astronomical know- 

 ledge during the past half-century has been due to spectrum analysis. 



The dark lines in the spectrum were first seen by Wollaston, who noticed 

 a few of them ; but they were independently discovered by Fraunhofer, 

 after whom they are justly named, and who, in 1814, mapped no fewer 

 than 576. The first steps in ' spectrum analysis,' properly so called, were 

 made by Sir J. Herschel, Fox Talbot, and by Wheatstone, in a paper read 

 before this Association in 1835. The latter showed that the spectrum 

 emitted by the incandescent vapour of metals was formed of bright lines, 

 and that these lines, while, as he then supposed, constant for each metal, 

 differed for different metals. ' We have here,' he said, ' a mode of dis- 

 criminating metallic bodies more readily than that of chemical examination, 



