A new main sewer, called the collecteur général de Clichy, was commenced in 1896, to supplement those of Asnières and Monceau, become insufficient; this passes under the Avenue and the Rue de Clichy to terminate at the Place de la Trinité. The prolongation of the line of the Orléans railway to the Quai d'Orsay, by means of a tunnel, has necessitated a very important modification of the sewers of the left bank of the river, which has had much to do with the lengthening of the work of excavation which has so greatly annoyed the dwellers on this side of the river in 1898 and 1899. It was understood that this excavating was to be done entirely underground, whereas it has blockaded many of the narrower streets, and even when it tunnels it contrives to raise the street level about a mètre and substitute a wooden floor, as along the Quai Voltaire. It is stated that this work will cost the railway company not less than five million francs. [Illustration: UNDERGROUND PARIS: LICENSED RAT-CATCHER IN A SEWER. After a design by G. Amato. Henri Dayre: Chasseur de rats de la Ville de Paris, fournisseur de toutes les Sociétés de France et de l'Étranger.] The diameter of the vault of the _égouts collecteurs_ varies between four and six mètres; that of the _égouts secondaires_ from two mètres to three mètres, seventy centimètres; that of the _égouts ordinaires_, including ten varieties, from one mètre to one mètre, seventy-five. The size the most in use has a diameter of one mètre, forty. The problem of purifying and utilizing the contents of the sewers, which were provisionally discharged into the Seine at Saint-Denis and at Asnières, occupied the attention of the municipality from the period of the establishing of the collecteurs, but the vigorous local opposition which was encountered greatly delayed the carrying out of these projects. Consequently, the purification of the river is not yet complete. On the sandy and arid plain of Genevilliers, situated in the first loop of the Seine, beyond Clichy, the experiment of fertilizing with this drainage was commenced in 1869. At present, the ground thus under cultivation includes some seven hundred and ninety-five _hectares_,--about two and a half acres each,--of which six belong to the city of Paris and constitute the model garden. The remainder is held by private individuals, who pay a rental of from four to six hundred francs the hectare. The distribution of the sewage is effected by agents of the administration in regular rotation, in three zones. In 1896, each hectare absorbed thirty-seven thousand and sixty-seven cubic mètres. All varieties of vegetables are grown, and this land, on which were raised formerly only meagre crops of rye and potatoes, is now a flourishing garden.