446 



• KNOWLEDGE . 



[Nov. 28, 1884. 



It will be seen that when M. Ad. de Boe, of Antwerp, 

 noticed the remuikalile a])pearance pictured at p. 325, the 

 Cordilleras were not at the edge of the earth's disc near (?„ 

 as my friend. Captain Noble, sugijested. Probably the 

 projection at a in M. de Boij's figure corresponded with 

 cloud-layers above the western parts of the North 

 Atlantic, near the shores of French Guiana, and northern 

 Brazil (north of the mouth of the Amazon), or it may have 

 been an effect of irradiation only. 



Fig. l. — The Luuar Eclipse of Oct. 4. 



Many pretty problems will suggest themselves to the 

 student in connection with the outline of the subject here 

 presented. But the majority of our readers will probably 

 consider that space ought not further to be given to a 

 subject belonging wholly to the geometry of astronomy. 



I shall take occasion shortly, however, to touch on the 

 way in which the sun, when geometrically behind the di>c 

 of the earth as seen from the moon, is brought into view by 

 refraction, — a matter about which much misapprehension 

 exists, even among professional (by which I mean official) 

 astronomers. 



CHAPTEKS ON MODERN DOMESTIC 

 ECONOMY. 



IV.— THE FKAMEWORK OF THE DWELLING-HOUSE 

 GENERAL PRINCIPLES OF COKSTRUCTIOX. 



TOBIN'S tubes, which we were led to mention inci- 

 dentally last week, whilst discussing the subject of 

 inlet ventilators, consist of wooden or metal tubes, a few 

 inches square and about five feet in length. They are 

 usually fixed in the corners of rooms, are open at the top, 

 and Gomoiunicate with the outer atmosphere at the bottom, 

 through air-bricks or gratings. It is sometimes advisable 

 to have the external portions of these pipes bent vertically 

 downwards, outside of the walls to which they are affixed 

 — a method which diminishes the quantity of au--borne dirt 

 which is liable at all times to enter the apartment in spite 

 of every care. The tubes need not interfere with the 

 artistic arrangements of the room. Indeed, they may be 

 made to add to its general beauty — e.g., in the drawing and 

 dining rooms they may be introduced beneath bottomless 

 vases of Doulton ware, or in many other ways to harmonise 

 with the internal decorations. 



A decided improvement upon these simple vertical tubes 

 is that known by the name of " Ellison's Expanding Venti- 

 lating Tubes." The principle of the " conical ventilator," 

 noticed in our last communication, is here added to the 



vertical tube in its expanding upper free extremity. Thi^ 

 lias the effect of spreading the air over a large area, and 

 thus preventing draughtiness. These ventilatirs ought to be 

 inserted through the wall at the height — from 6 It. to 8 ft. 

 above the floor — at which they are to be fixed ; it is not 

 necessary, as in the long " Tobin's tubes," to carry them 

 upwards from the level of the floor. Mr. Ellison, the 

 inventor, recommends that they should be placed above 

 the spaces allocated to seats, or similar low pieces of furni- 

 ture. They are made of zinc, either with or without 

 closing and opening valves, and are to be recommended 

 on account of their cheapness, durability, and effective 

 action. 



We have considered how fresh air ought to be conveyed 

 into the apartments of a house by simple passive means, 

 and it now remains to provide for the removal of the 

 vitiated air in the establishment of a rational system of 

 house-ventilation. A suitable outlet ought to be made 

 beneath the cornice, or at the highest available part, a few 

 inches below the ceiling in the smoke-flue, and a mica 

 ventilator, or other valvate arrangement, fixed therein in 

 such a way as to prevent the regurgitation of smoke and 

 its unpleasant passage into the house. Smoky and sluggish 

 chimneys, however, are very apt to give great trouble with 

 such an apparatus, which is best adapted to work in con- 

 junction with chimneys which have a good upward daught, 

 and are not exposed to tbe influence of the prevailing 

 winds through the use of well-devised cowls and protectors. 

 It is a very difficult matter to fix an outlet ventilator which 

 shall work with any degree of success in opposition to the 

 chimney in an opening made through an external wall, 

 otherwise the aerial circulation would be considerably 

 simplified. 



The removal of heated air and the products of com- 

 but-tion from gas and other analogous illuminators can be 

 effected by the simple expedient of inverted tubes with 

 expanded mouths placed directly over the flames, and con- 

 structed in such a way as to lend a pleasing and artistic 

 aspect to the room. We shall give a few special illustra- 

 tions of this when we come to treat of the question of 

 domestic lighting. 



It is a very common error to suppose that lofty ceilings 

 are conducive to good ventilation in projjortion to their 

 greater height. Such is not the case ; the contaminated 

 air, in consequence of its relatively high temperature, 

 ascends ; it goes on parting with its heat, aud, if the ceiling 

 is very high, it descends with redoubled speed iu virtue of 

 its greater specific gravity, instead of escajni'g through the 

 outlet ventilator, whilst its warmth is still sufficient to 

 cause it to ascend through the aperture in the chimney flue. 

 In a moderately low-ceilinged room the foul air escapes 

 readily, and the purity of the atmosphere is thus secured. 

 Hence it is advisable, volume for volume, to have breadth 

 and width rather than height. 



The fireplaces in a house exercise an important influence 

 over its ventilation. As the kitchen fire is the one which 

 is most constantly employed, it often happens that its 

 action induces a down-current in the other rooms, which 

 may reach from the highest floor even to the very basement 

 It is, therefore, important to isolate the several apartments 

 and passages of a house as much as possible, in the event 

 of communicable disease from one room to another through 

 these general draughts. 



We have laid great stress upon the ventilation of in- 

 habited apartments, because it is a subject which seems to 

 be almost universally neglected in practice. We have 

 endeavoured to show how all the benefits of a pure 

 atmosphere indoors can be easily gained, through the use 

 of simple and inexpensive apparatus, and we are confident 



