224 ANNUAL OF SCIENTIFIC DISCOVERT. 



them and our own earth, and are led to the noble idea that Nature 

 constnu'ts evervwhure out oCthe same materials. Bodies, so dis- 

 tant that the a.^^tronomer fails to give us an idea of their remote- 

 ness, are brought, as it were, into our grasp, and are anal3zed 

 with certainty. We recogni/e the same elements in them that 

 compose the soil we tread, the water we drink, the air we breathe. 



And what ai'e these materials? Chemists enumerate to us 

 sixty-eight elementary l)odies, that is, substances not composed 

 of anything else, and that cannot be further decomposed. Such 

 are the gases: oxygen, nitrogen, iiydrogen, etc.; the liquids: 

 mercury, bromine, etc.; the solids: sulphur, iron, gold, etc. One 

 is liltcen times lighter than the air, another twenty-one times as 

 heavj- as water. Truly, Nature has variety enough to choose 

 from, for out of sixty-eiglit elements how many combinations 

 may not l)e made? But this very variety creates at once a sus- 

 ])iri()n that the ultimate elementary bodies are not in fact so 

 numerous. 



Among the reasons for doubting tlie multiplicity of elementary 

 bodies, it may be stated: 1. That many of them are so nearly 

 identical thai it requires a good chemist to distinguish one from 

 another. 2. That in our own times a number of elements have 

 been stricken from the list, iiaviiig been found to be compound 

 bodies. 3. That by quite trivial means one elementary substance 

 may be made to assume a form having ])roperties totally distinct 

 from those it originally possessed. 4. That we can form, from 

 two or more elements, bodies which have the attributes of ele- 

 ments, a case in point being cyanogen. 5. That the infinite variety 

 of organic substances, such as the various tissues of the bodies 

 of animals and plants, diverse as they ai'C, all are formed princi- 

 pally from four elementary bodies. A multitude more of such 

 arguments might be advanced ; but the general conclusion which 

 they indicate can be summed up in a line. All the sixty-eight 

 elements may be compounds of perhaps only two or three ele- 

 ments, — may even be modifications of a single type of matter. 

 But any fiuther consideration of this part of the subject would ■ 

 lead us into an examination of the nature of matter, and its atomic 

 constitution, and with that we have not room to deal. 



But we will penetrate yet a step further into space. The stars, 

 it has been stated, are exceedingly remote. Let us examine bodies 

 so distant that the stars are near neighboi-s compared with them. 

 Clusters, resolvable nebuljB, ti'ue nebulse, shall carry us as far from 

 the earth into space as the eye can see. 



To the naked eye, or in a telescope of low magnifying power, 

 there are visible in the sky certain patches of diffused light, differ- 

 ing in appearance from the glittering stars. Some, when examined 

 with a higher power, are seen to be resolved into an aggi-egation 

 of stars ; some, by the use of the highest attainable magnifying 

 power, on the finest nights, are Avilh difficulty resolved, while 

 some resist every attempt. It is with the last that we are more 

 particularly concerned. 



The great i-etlecting telescope of Lord Rosse is well known. It 

 is six feet in aperture, and fifty-four feet in focal length. By its 



