THE BOIS DE BOULOGNE. 



31 



long time on tlie surface of the roacls^ &c., before being 

 absorbed ; to have remedied tbis by means of sewers would 

 have cost about 160^000/.^ so the plan was adopted of con- 

 structing a number of tanks at intervals_, on an average^ of 

 200 metres, and capable of containing from ten to twenty 

 cubic metres of water each. These tanks are generally 

 circular in form and crowned by a truncated cone — a form 

 which of course requires less mason^s work than the rec- 

 tangular, the latter being adopted only when large trees in- 

 terfere with the plan. These tanks are shown in fig. 12. The 

 rectangular cisterns measure from four to six metres in 

 length, one to two metres in width, and two to three metres 

 in depth; they are arched at the top, and, like the circular ones, 

 provided with a trapped hole, which serves, first, to with- 

 draw the centrings, and afterwards to clean out the cisterns 

 if they become choked with refuse carried down by the 

 water ; the floor is uncovered, and barbicans are left in the 

 footwalls to aid the escape of the water. These cisterns 

 are placed either under the footpaths or in side alleys, so as 

 not to interfere with the grass or the flower beds. The 

 water is conveyed to the cisterns by means of drain pipes 

 4in. exterior diameter, the flrst joint being embedded in a 

 mouthpiece of Portland cement, shown in the engraving. 

 These mouthpieces are nearly 20in. in length ; they are cast 

 in wooden moulds, and cost 2f. 90c. per metre. 



Not far from the lower lake, and at about the centre of 

 the Bois, occurs the Pre Catalan — an enclosed space, occa- 

 sionally the scene of fetes, having several refreshment rooms, 

 an open-air theatre, and a peculiar feature in the form of 

 a cow-house, containing about eighty milch cows. The 

 milk is sold to those who frequent the place, especially to 

 horsemen who ride out from Paris for exercise in the early 

 morning, and call here on their way to have a draught of 

 new milk. These features, however, are kept well in the 

 background, and the lolace generally bears the appearance 

 of an ornamental garden, well worthy of a few minutes^ 

 inspection from any horticultural visitor who is traversing 

 the Bois or on the fashionable drive, which is near at hand. 



Gardeners may be interested to learn that every year. 



