SCIENCE. 



(No. 2), Raphidium (No. 9), Tetraspora (No. 10), and 

 other Algae as Chlamydococcits (No. 11) or Ulothrix. 

 Infusoria equally (Chatonotus |No. 20], Rrachytons [No. 

 23], Euglena [No. 12]) and several specks of Diatoms 

 already named or a little different. But that which is 

 striking is the already notable quantity of organic re- 

 mains, fragments of plants (No. 24), mycelium of mush- 

 rooms (No. 18), and an eel (No. 17), moving about in 

 the middle of all this multitude, and, in fig. 2, crossing 

 a spicule of Spongille (No. 15). 



The water taken at the bridge of Austerlitz is more 

 chaiged with detritus; the purifying alga; disappear and 

 diatoms are rare. It is infusoria and their bodies which 

 predominate, then finally there are remains of tissues of 

 linen or cotton, of vegetables in decomposition, etc., 

 which the waters of Bercy, of Rap(-e and Bievre brought. 



If now the water of the pump of Chaillot is examined 

 (fig. 3), the maximum contamination of the Seine is 

 attained. (If this is not, however, the water taken at 

 Saint-Ouen ; but at this place the stre am has received, as 

 is known, the sewer collector at Asnieres, which is a 

 serious cause of infection of the water for a long dis- 

 tance.) The quantity of carbonic acid has already in- 

 creased, and the oxygen grown ltss. 



In the Chaillot water (fig. 3) there are scarcely any more 

 algae, here and there remains of conferva {Claduphora 

 [No. 14] or some rare specimens of more reduced species 

 (Pandorina [No. 1]), Clilanydococcus [No. 5]. Sirureila 

 [No. 2], Stanroneis [No. 3], Epithemia [No. 4]), jet 

 most often there is only the silicious carapace, void of 

 endochrome, of these last diatoms. On the other hand, 

 the deposit of detritus is dominant in r: muscular fibres, 

 (No. 10), vegetable cellules (No. 11). then myceliums of 

 inferior fungi, and lastly eels (No. gj. Yet there 

 is still more : some microscopic crustaceans ap- 

 pear (Daphnia pulex and otheis [Nos. 7 and 8]), the 

 whole associated with earthy or indeterminable re- 

 mains. 



M. Neuville disputed the opinion of M. Franklandwho 

 refuses to admit that rivers purify themselves. He main- 

 tains, which seems to be perfectly demonstrated, that 

 after a tranquil journey without receiving other impurities, 

 a river purifies itself, little by little, by deposition, either 

 on the bottom of the bed, or on the banks, of the sub- 

 stances which it held in solution. The harmful matters 

 held in solution are eliminated and they disappear ; the 

 carbonic acid becomes exhausted little by little and the 

 oxygen, on the other hand, returns in proportion. 



During the war of 1870-71, the forced stopping on the 

 rivers which habitually received the injections of factories 

 and of industries polluting these streams, had changed 

 their conditions. Thus the Bievre, tainted from Arcueil 

 to its arrival in the Seine at Paris, had again become lim- 

 pid, and fish had made a home in it, coming from the 

 parts above Arcueil, although however the bottom of the 

 bed of the Bievre was at this moment covered by a thick 

 bed of mud nauseating at ordinary times. 



The water of the Seine at Saint-Ouen became again 

 more impure than any other part ; but, as has been said, 

 this was due to the sewer collector of Asnieres. The car- 

 bonic acid which, at the bridge of Austerlitz, was repre- 

 sented by 16.2 by hund. cube, reached here the propor- 

 tion of 65, that is to say the maximum for the waters of 

 Paris. Liv ing creatures here are very rare ; but the re- 

 mains of stuffs : linen, yarn, cotton, animal and vegetable 

 fibres abound here. It is no longer a deposit, it is a real 

 soup. The chlorides, the sulphates, and the sal ammo- 

 niacs, as well as sulphuretted hydrogen, are largely repre- 

 sented here. Finally further on, where the Seine passes 

 by St. Denis and receives from it some quantity of refuse, 

 vegetation is no longer found in it, and the bottom of the 

 stream is nothing but a blackish and contaminated mud, 

 as M. G6rardin observed it. 



The canal waters of Ourcq have been for a long tim 

 the principal source of the supply of Paris. They ar 



selenitic ; but yet M. Neuville does not consider them the 

 worst waters used in the city. A great number of algae 

 live in them, this being in their favor, and their relative 

 tranquillity is also one of the causes of this notable growth 

 of vegetation. The numerous boats which sail on these 

 waters and the warehouses bordering this canal, where un- 

 loading is done, must prove sources of pollution of 

 these waters? Their hydrometric degree is 30° to 31 

 while the mean of the waters of the Seine is between 1 7 and 

 20 , but this does not constitute in the eyes of M. Neuville 

 a plausible reason of inferiority for the waters of Ourcq. 

 It is their stagnation which ought to be the dominant 

 cause of their depreciation. 



Figure 4 represents the composition, in organisms, of 

 the waters of the V'anne. It is, according to microscopi- 

 cal observations as well as according to the official reports, 

 the best of the waters of Paris. M. Belgrand says : 

 " comparison was not possible between the excellent 

 waters of the Vanne and those of the Seine and the 

 Ourcq, which, warm in summer, cold in winter, agitated 

 and not transparent in all seasons, are besides tainted more 

 and more by the residue from industrial and human refuse. 

 After a journey of 176 kilometres by means of closed inlets, 

 the waters of the Vanne arrive at the reservoirs of Mont- 

 souris and can furnish 100,000 metres cubes of water in 

 24 hours. Limpid, fresh, exempt from organic matters, it 

 unites all perfections, says M. Neuville, it is water that I 

 wish to see distributed in all Paris." 



Several alga: of good quality, such as Ulothrix (No. 7), 

 Mclosisa (No. 2), Mcridion (No. 1), Navicula"No. 3), 

 and Synedra, are the respectable inhabitants of these 

 waters ; here and there some vegetable growths and earthy 

 remains, and finally some crystals of carbonate or sul- 

 phate of calcium (No. 11). 



The waters of the Dhuis (fig. 5) only arrive at the reser- 

 voirs of MOnilmcntant, associated with those of the Sur- 

 melin. At their point of junction, those of the Dhuis 

 appear rather pute but never heless they are agitated and 

 have need of rest. It is a remarkable thing that the 

 microscope reveals no alga; in them; on the other hand, 

 organisms of another order are met with, some filaments 

 of Mucoiinees (No. 1), myceliums (No. 2), and some 

 earthy or organic remains (Nos. 4, 5, 6). According 

 to all appearances, these waters are not sufficiently 

 oxygenated, and a journey a little prolonged in the open 

 air and in the light will make them perfect. 



Rivalling with the waters of the Vanne for purity and 

 freshness, the reputation of the waters of Arcueil has been 

 known for a long time (fig. 6); they were so named be- 

 cause they flow through the valley of the Bievre over an 

 aqueduct at Arcueil. But in truth, they have come from 

 the village of Rungis since the Roman epoch, for these 

 ate the waters which supplied the baths called baths of 

 Julius Caesar or therma; of Cluny. To the Roman aque- 

 duct, of which several traces remain, succeeded that 

 which can now be seen, built by Desbrossein 1624, which 

 has to conduct the waters of Rungis to the palace of 

 Luxembourg and in the Saint-Jacques quarter. Advan- 

 tage is taken of this monument, solidly constructed, to 

 build above it the new aqueduct for the waters of the 

 Vanne, which are conducted to the basin of Montsouris. 

 M. Neuville says " with difficulty can be seen in them, 

 several Vorticelles and Oscillaries (Nos. 1, 5, fig, 6), then 

 several diatoms (Gomphonema [No. 3], Nitzschia [No. 2]) 

 and lastly some salts of calcium, chrystallized and pre- 

 cipitated from their solution by the loss of a portion of 

 carbonic acid. It is water of good quality, which can be 

 improved by means of successive cascades, and it is 

 unfortunate that we have not more of it. 



The sources of the Nord of Paris offer but little in- 

 terest. Given up to the consumption of the inhabitants 

 of Paris from the end of the twelfth century, they were 

 for a long time the only waters which supplied the foun- 

 tains of the capital. I hese, with the waters of Arcueil 

 are the most ancient known. They are furnished by 



