518 



♦ KNOWLEDGE 



[Dec. 26, 1884. 



of rocks of volcanic origin underlying all the other rocks of 

 Wales, and therefore of Pre-Cambrian age, has led him to 

 consider that the Churuwood rocks, too, may be of this 

 enormous antiquity. From the study of the Silurian rocks of 

 the Lake district, I, too, once believed them to be identical 

 with our Leicestershire strata, but I now feel certain that 

 the latter are of Pre Cambrian age. Is it possible that any 

 mistake can have been made in mapping the strata in Cum- 

 berland and Westmorland, and that they, also, are of this 

 high antiquity ■? 



{To he continued.) 



OTHER WORLDS THAN OURS. 



A WEEK'S CONTERSATION ON THE PLURALITY OF 

 WOBLDS. 



By Mons. de Fontenelle. 



with notes by richard a. proctor. 



THE FOURTH EVENING {rontinued). 



" A FTER Mercury comes the sun ; but there is no pos- 



Lx. sibility of peopling it, nor no room left for a 

 wherefore. By the earth which is inhabited, we judge 

 that other bodies of the same nature may be likewise 

 inhabited : but the sun is a body not like the earth, or any 

 of the planets ; the sun is the source or fountain of light ; 

 which, tho' it is sent from one planet to another, and 

 i-eceives several alterations by the way, yet all originally 

 proceeds from the f-un : he draws from himself that 

 precious substance which he emits from all sides, and which 

 reflects when it meets with a solid body, and spreads from 

 one planet to another those long and vast trains of light 

 which cross, strike thro', and intermingle in a thousand 

 different fashions, and make (if I may so say) the richest 

 tissues in the world. 



" The sun likewise is placed in the center, from whence, 

 with most convenience, he may equally distribute, and ani- 

 mate by his heat. It is then a particular body, but what 

 sort of body, has often puzzled better heads than mine. It 

 was thought formerly a body of pure fire ; and that opinion 

 passed current till the beginning of this age : when they 

 perceiv'd several spots on its surface. A little after they 

 had discover'd new planets (of which hereafter), which 

 some say were those spots ; for those planets moving round 

 the sun, when they tiirn'd their dark half to us, must 

 necessarily hide part of it : and had not the learned, with 

 these pretended planets, made their court before to most of 

 the princes in Europe, giving the name of this prince to 

 one, and of that prince to another planet, I believe they 

 would have quarrell'd who should be master of these spots, 

 that they might have nam'd them as they pleas'd."* 



" 'Twas but t'other day," says the lady, " you were 

 describing the moon, and call'd st-veral places by the names 

 of the most famous astronomers. I was pleas'd with the 

 fancy : for since the princes have seiz'd on the earth, 'tis 

 fit the philosophers (who are as proud as the best of 'em) 

 should reserve the heavens for themselves without any 

 competitors." 



" Oh ! trouble not yourself," said I, " the philosophers 

 make the best advantage of their territories ; and if they 

 part with the least star, 'tis on very good terms : but the 

 spots on the sun are fallen to nothing. 'Tis now discover'd 

 that they are not planets, but clouds, streams, or dross, 

 which rise upon the sun, sometimes in a great quantity, 

 sometimes in a less ; sometimes they are dark, sometimes 

 clear ; sometimes they continue a great while, and some- 

 times the 7 disappear as long. 



* Thoy called them the Bourbonian stars, — R. P. 



" It seems the sun is a liquid matter ; some think, of 

 melted gold (!), which boils over as it were continually 

 and by the force of its motion calls the scum or dross on 

 its .surface, where it is consum'd, and others arise. Imagine 

 then what strange bodies these are, when some of them 

 are as big aa the earth. What a vast quantity must there 

 be of this melted gold ! and what must be the extent of 

 this great sea of light and fire which they call the sun 1 



"Others say, the sun appears thro' their telescopes full 

 of mountains, which vomit fire continually, and are joined 

 together like millions of Etna's. Yet there are those that 

 say, these burning mountains are pure vision, caus>'d by a 

 fault in the spectacles ; but what shall we trust, if we mtist 

 distrust our telescopes, to which we owe the knowledge of 

 80 many new objects ? But let the sun be what it will, it 

 cannot be at all proper for habitation ; and what pity that 

 is ! for how pleasant would it be ! You might then be at 

 the center of the universe, where you would see all the 

 planets turn regularly about you ; but now we know 

 nothing but extravagant fancies, because we do not stand 

 in the proper place. There is but one place in the world, 

 where the study or knowledge of the stars is easily obtain'd, 

 and what pity 'tis there is nobody there ! " 



" You forget yourself, sure," says she ; " were you in 

 the sun you would fee nothing, neither planets nor fixed 

 stars : doth not the sun efface all ? So that could there be 

 any inhabitants there, they might justly think themselves 

 the only people in Nature." 



" I own," said I, " my mistake : I was thinking of the 

 situation of the sun, and not of the effect of its light : I 

 thank you for your correction ; but must take the boldness 

 to tell you, that you are in an error as well as myself : for 

 were there inhabitants in the sun, they would not see at 

 all ; either they could not bear the .strength of its light, or 

 for want of a due distance, they could not receive it ; so 

 that things well consider'd, all the people there must be 

 stark blind, which is another reason why the sun cannot 

 be inhabited. But let us pursue our voyage." 



{To le con<tn««<».) 



PLEASANT HOTIKS WITH THE 



MICROSCOPE. 



By Henry J. Slack, F.G.S., F.R.M.S. 



IX holiday times it is well to make experiments and 

 observations which are sure to interest the young folks. 

 One of the best that can be suggested is to form a so-called 

 lead-tree, portions of which make very pretty objects for 

 the microscope. The proceeding is very easy. Get a clear, 

 round, glass bottle, holding six ounces. Take two drachms of 

 acetate of lead, and dissolve in six ounces ot distilled water. If 

 the water is pure, it will dissolve the salt without milkiness ; 

 but it is seldom pure enough for this. The solution, if not 

 quite clear, should be allowed to stand until a deposit 

 settles to the bottom, and the clear part may then be poured 

 off for use. Take a thin strip ot zinc, about a quarter of 

 an inch wide, which should be made bright by rubbing with 

 a little sand or Flanders brick-dust, or by wiping with a 

 rag moistened with dilute hydrochloric acid. Make one 

 end of the zinc sharp, and force it into a cork that fits the 

 bottle. The strip of zinc should be long enough for one 

 inch of the metal to be immersed in the fluid. The acetic 

 acid of the lead salt immediately attacks the zinc, forming 

 a soluble acetate of that metal. The lead is precipitated in 

 a beautiful feathery foim. As soon as an elegant little 

 t'lft is seen, withdraw the cork, and scrape oflf the lead on 

 to a piece of blotting-paper. As soon as it is dry, select a 



