220 



♦ KNOAVLEDGE ♦ 



[Sept. 12, 1884. 



the water, but prolongs the efficacy and speed of the filtra- 

 tion. As a chemical reactor, carho calcis is equal, if not 

 superior, to any other medium of its kind. It removes iron, 

 lead, sewage poisons, and even ammonia and sulphuretted 

 hydrogen. It also reduces the hardness of water to an appre- 

 ciable extent. As soon as it becomes foul, it may be replaced 

 by a fresh charge at a trifling cost, and thus entirely over- 

 comes the objection to the use of organic carbon as a filtering 

 agent. 



The requirements of a good drinking water are that it 

 shall be tasteless, odourless, colourless, cool, and refreshing ; 

 that, in order to be so, it shall be ai'i-ated with purified air 

 or carbonic acid gas ; and that it shall neither be too hard 

 nor too soft, and be free from all septic or other dele- 

 terious impurities. The filter that can modify foul water 

 which is alike disagreeable to the eye, nose, and mouth, 

 and which, when it enters the alimentary system, becomes 

 dangerous, and endow it with all the qualities of good, 

 wholesome water, and which, moreover, is within the reach 

 of the humblest cottager, needs no word of commendation 

 — it speaks for itself. Such a filter is Maigoen's. 



It is not, then, a matter for astonishment that the Exe- 

 cutive Council have deemed the " Filtre Rapide" worthy 

 of the place they have assigned to it, and visitors to the 

 Exhibition may now drink freely from the fountains with- 

 out any fear of being injured thereby. Mr. Maignen has in- 

 formed us that he has recently furnished the " Nile 

 Expedition Commission" with 800 filters. Each instru- 

 ment is capable of purifying from ten to twenty gallons per 

 hour, measures 18 by 12 by 10 inches, and weighs only 

 1 G lb. Two buckets are telescoped round the filter, one 

 furnished with a long strap to draw the water from the 

 river, and the other placed under the filter to receive the 

 purified water. We believe that Sir Peter Lumsden has 

 also taken a few of these valuable travelling companions 

 with him to Afghanistan. Doubtless the merits of the 

 Filtre Rapide will soon make it a universal favourite, 

 when the village smithy may be flanked on one side by its 

 rural "Filter House" (Fig. 31), and water companies seek 

 its aid to give us better water. 



OTHER WORLDS THAN OURS. 



A WEEK'S CONVERSATION ON THE PLURALITY OF 



WORLDS. 



By Mons. de Fontenelle. 



with notes bt richard a. proctor. 



THE SECOND EVENING (continued). 



" X)UT what do you think," said she, "of the people in 

 JlJ the moon ; are they as fearful of an eclipse as we 

 are "i It would be a good jest to see the Indians there up 

 to the neck in water ; that the Americans should believe 

 the earth angry with them ; the Greeks fancy we were 

 bewitched, and would destroy their plants ; in short, that 

 we should cause the same consternation among them, as 

 they do here." 



" And why not f' said I. " I do not doubt it at all ; for 

 why should the people of the moon have more wit than 

 we 1 What right have they to aflVight us, and not we 

 them 1 For my part, I believe that since a prodigious 

 company of men have been, and still are such fools to 

 adore the moon, there certainly are people in the moon 

 that worship the earth, and that we are upon our knees 

 the one to the other." 



" But sure," said she, " we don't pretend to send any 

 influences to the moon, and to give a crisis to her sick ; 



if the people have any wit in those parts, they will soon 

 destroy the honour we flatter ourselves with, and I fear we 

 shall have the disadvantage." 



" Fear it not, madam," said I ; "do you think we are 

 the only fools of the universe? Is it not common for 

 ignorance to spread itself everywhere t 'Tis true, we can 

 only guess at the folly of the people in the moon, but I no 

 more doubt it, than I do the most authentick news that 

 comes from thence." 



" What news comes from thence ? " said she. 



" That which the learned bring us," I replied, " who 

 travel thither every day with their tubes and telescopes ; 

 they will tell you of their discoveries there, of lands, seas, 

 lakes, high mountains, and deep abysses." 



"I fancy, indeed," said she, "they may discover mountains 

 and abysses, because of the remarkable inequality; but how 

 do they distinguish lands and seas 1 " 



" Very easily," said I ; " for the waters letting part of 

 the light pass thro' them, send back but a very little, so 

 that they appear afar ofllike so many dark spots* ; whereas 

 the lands being solid, reflect the whole light, and appear 

 to be more bright and shining. The illustrious Monsieur 

 Cassini, a most compleat astronomer, has discovered 

 something in the moon which divided, then reunited, 

 and sunk in a kind of well : we may very probably 

 suppose this was a river. Nay, they pretend to be so 

 well acquainted with the several places, that they have 

 given them all names: one they call Copernicus, another 

 Archimedes, another Galiteus : there is the Caspian Sea, 

 the Black Lake, the Porphyrite Mountains ; in short, they 

 have publish'd such exact descriptions of the moon, that a 

 very almanack-maker will be no more to seek there than I 

 am in Paris." 



" I must own, then," said the Marchioness, " they are 

 very exact ; but what do they say to the inside of the 

 country 1 I would very fain know that." 



" 'Tis impossible," I replied ; " the most learned astro- 

 nomers of our age cannot inform you. You must ask that 

 of Astolfo, who was carried into the moon by St. John. I 

 am going to tell you one of the agi-eeable follies of Ariosto, 

 and I am confident you will be well pleased to hear it. I 

 must confess he had better have let alone St. John, whose 

 name is so worthy of respect ; but 'tis a poetical licence, 

 and must be allowed. The poem is called ' Orlando 

 Furioso,' is dedicated to a Cardinal, and a great Pope has 

 honoured it with his approbation, which is prefixed to 

 several of the editions. This is the argument : Orlando, 

 nephew to Charlemain, runs mad because the fair Angelica 

 prefers Medore before him. Astolfo, a knight-errant, find- 

 ing himself one day in the terrestrial Paradise, which was 

 upon the top of a very high mountain, where he was carried 

 by his flying horse, meets St. John, who tells him, if he 

 would have Orlando cured, he must make a voyage with 

 him into the moon. Astolfo, who had a great mind to see 

 new countries, did not stand much for entreaty ; and im- 

 mediately there came a fiery chariot, which carried the 

 apostle and the knight up into the air. Astolfo, being no 

 great philosopher, was surprised to find the moon so much 

 bigger than it appeared to him when he was upon the 

 earth ; to see rivers, seas, mountains, cities, forests, nay, 

 what would have surprised me too, nymphs hunting in 

 those forests ; but that which was most remarkable was a 

 valley where you might find anything that was lost in our 

 world, of what nature soever — crowns, riches, fame, and 

 an infinity of hopes ; the time we spend in play and in 

 searching for the philosopher's stone ; the alms we give 



* It is interesting to find Kepler's notion that tlie dark parts of 

 the moon are seaa prevailing after Cassini's time. — R. P. 



