HOME GARDENS FOR SMOKY TOWNS. 361 



I was much interested on finding that the long experience 

 and many trials of Dr. Percy and his assistant engineer, Mr. 

 Prim, have resulted in the selection of the identical material 

 which I have chosen, and with which the above-described 

 experiments have been made. A wall of such canvas 

 surrounds a lower region of the Houses, and all the air that 

 is destined to have the privilege of being breathed by 

 British legislators is passed through this vertical screen, for 

 the purpose of separating from it the sooty impurities that 

 constitute the special abomination of our metropolitan 

 atmosphere, and that of our great manufacturing towns. 

 The quantity of sooty matter thus arrested is shown by the 

 fact that it is found necessary to lake the screens down once 

 a week and wash them, the wash water coming away in a 

 semi-inky condition. 



I anticipate that the conservatory filters will rapidly clog, 

 and, therefore, require washing. This may easily be done 

 by means of a jet from a hand-syringe directed from within 

 outwards, especially if the slope of the roof is considerable, 

 which is to be recommended. The filtering screen of the 

 Houses of Parliament is made by sewing the canvas edges 

 together, to form a large continuous area, then edging the 

 borders of this with tape, and stretching it bodily on to a 

 stout frame. This method may be found preferable to that 

 which I proposed above, and cheaper than I have estimated, 

 as only very light intermediate cross-pieces would thus be 

 required, merely to prevent bagging, the parliamentary 

 quartering above described being nine feet apart instead of 

 three. This would reduce the cost of timber to about one 

 half of the above estimate.* The perpendicular walls of a 

 conservatory, where such are required, may certainly be 

 made thus, and I think the roof also, if the slope is con- 

 siderable. Or, if in demand, the material may be made of 

 greater width than the three feet. 



So far, I have only mentioned back-yards; but, besides 

 these, there are many very melancholy front areas, called 



* Subsequent experiments induce me not to recommend this econ- 

 omy, on account of the bagging which results from excessive width 

 between the frames; 3 feet should not be exceeded. 



