426 



♦ KNOWLEDGE ♦ 



[Nov. 21, 1884. 



Auriga, the Charioteer (a, 



Capella) 

 Ursa Major, the Greater 



Bear (n, (i, the Pointers). 

 Canes Venatici, the HuntirKj 



Doijs (a, Cor Caroli). 

 Coma Berenices, Queen 



Berenice's Hair. 

 Bootes, the Herdsman (n, 



Arcttirus). 

 Corona Borealis, the Nor- 



them Crown. 

 Serpens, the Serpent. 

 Hercules, the Kneeler. 

 Lyra, the .Lj/re (o, Vcjn). 

 Cy<jnus, the Swan (a, 



Arided ; j3, jliijtres). 

 Pejastjs, the Winged Horse. 

 Andromeda, the C/iai»e<2 



Lady. 

 Triangula, the Triangles. 

 Aries, the Roin. 

 Ta«rits, the BuU (o, jlide- 



baran; 7], Alcyone, chief 



Pleiad) . 

 Gemini, the Twins (a, 



Castor ; (i, Pollux). 

 Cancer, the (Vab (the 



cluster is the Beehive). 

 Leo, the Lion (a, iJejuin*). 

 FiV<70, the Virgin (o, Spica). 



(J. 



7. 



8. 



9. 



10. 



11. 



12. 

 13. 

 14. 

 15. 



16. 

 17. 



18. 

 19. 

 20. 



21. 

 22. 



23. 



24. 



25. Libra, the Scales. 



26. Ox'hiuchus, the Serpent 



Holder. 



27. j4(;«i!a,theEa5iJe(a,.4Ztetr). 



28. Delphinus, the Dolphin. 



29. ^(jitarius, the ITa/cr Carrier. 



30. Pisces, the FisAes. 



31. Cef«s, the Sea Jfonsfer (o, 



Jftra, remarkable va- 

 riable) . 



32. Eridanus, the itiver. 



33. Orion, the Giant Hunter 



{a, Betelgeu.v ; fi, Rigel). 



34. Canis 3f'7ior, the Lesser Dog 



(a, Procyon). 



35. Hydra, the Sea Serpen* (a, 



Alphard) . 



36. Crater, the Cup (a, Alkes). 



37. C'orvMs, the Croit'. 



38. Scorpio, the Scorpion (a, 



.47i(are«). 



39. Sagittarius, tlie Archer. 



40. C'opricor/ius, the Sea Goa(. 



41. Piscis Australis, the fioit- 



themFish (a,Fomalhaut). 



42. Lepus, the Hare. 



43. Columha, the Cove. 



44. Cants Jlfojoi-, the Greater 



Dog (a, Sirius). 



45. jlrjo, the Ship. 



CHAPTERS ON MODERN DOMESTIC 

 ECONOMY. 



III.— THE FEAMEWOEK OF THE DWELLING-HOUSE 



(continued). 



GENERAL PRINCIPLES OF CONSTRUCTION. 



IT is now generally understood that the admission of 

 fresh air into buildings and its maintenance therein 

 under suitable conditions of temperature and pressure, is 

 almost, if not quite, as important as the exclusion of damp 

 and the choice of a thoroughly sound foundation and sub- 

 basement. 



Pure air consists of about 79 per cent, of oxygen, 

 and 21 per cent, of nitrogen by measure, with 1 part 

 of carbonic-acid gas in every 2,.500 parts of the atmo- 

 sphere. Air of this nature, at a temperature varjiog 

 from 55° to 65° Fahr., may be considered to be typically 

 perfect for the promotion of health in the average human 

 being. To secure and maintain such an atmosphere in the 

 dwelling-house is a practical impossibility, for reasons which 

 we shall give hereafter ; but it must not be imagined that, 

 because of this, an insalubrious state of affairs must in- 

 evitably follow. There is a margin, and a very wide 

 margin, within the bounds of which freedom from all evils, 

 arising from impure air, is available. 



The process of slow combustion which goes on in the 

 animal body requires the presence of oxygen ; and the 

 nitrogMi of the air acts as a dilutant. A somewhat similar 

 combustion goes on more rapiilly in the employment 

 of fires, gas, and oil flames. The animal body, again, 

 throws off waste products from its other glandular organs, 

 such as the secretion of noxious liquids and gases, which 

 emanate from the skin, tegumentary organs, and mucous 

 membranes. 



A qualitative analysis of the products of combustion in an 

 ordinarily-inhabited apartment would show that the air is 

 vitiated with carbonic acid, the vapour of water, waste 

 animal tissues, carbon in the form of smoke and soot, car- 

 buretted and sulphuretted hydrogen, and a trace of various 

 salts. To these must be added the indirect accession of 

 germs of putrefaction, and, may be, of disease, together 



with vapours and ga.se8 from vegetable matters and the 

 external atmosphere. 



It has been estimated that, on an average, the adult 

 human being inhales from about 15 to 20 cubic feet of air 

 during the course of an hour, and exhales almost an equi- 

 valent amount of carbonic acid gas. During that period, 

 also, about 2^ oz. of aqueous vapour, charged with effete 

 matters, are given off from the respiratory passages, other 

 mucous membranes, and the skin. It has also been calcu- 

 lated that a jet of gas, which consumes 5 cubic feet per 

 hour, uses up all the oxygen fiom 50 cubic feet of air, and 

 produces 5 cubic feet of carbonic acid, 10 cubic feet of 

 aqueous vapour, and an appreciable proportion of carbon 

 particles and carburetted and sulphuretted hydrogen. Yet, 

 nevertheless, the generation of impurities from any given 

 flame is not directly proportional to the size of the flame, for 

 a jet turned on to three-quarters of its full extent will con- 

 sume almost as much oxygen as one fully turned on ; so 

 that it is more advisable to employ a few burners fully 

 turned on, than a larger number partially turned down, 

 in the production of a given degree of illumiaation.* 



From what has been stated, it is evident that the com- 

 bined influence of natural and artificial combustion tends to 

 render the atmosphere unwholesome, and that it does so 

 from a variety of causes. It hus, moreover, been found 

 that the quantity of carbonic acid gas in the atmosphere 

 serves as an index to the suitability of the latter ; not so 

 much on account of its direct action as a poison to the 

 respiratory system of animals, as being in constant associa- 

 tion with other more powerfully noxious elements. Physio- 

 logical biologists have shown that the processes of life in 

 both plants and animals are essentially the same. The old 

 notion that plants respire the products of exhalation from 

 animals is not strictly correct. The carbonic acid given off 

 in the process of animal respiration would act as a poison 

 upon that animal if it were re-inhaled ; but taken as a food 

 into the alimentary system, it would act beneficially. Kow, 

 that is exactly what happens in the vegetable kingdom ; 

 the carbonic acid resultiug from the expiration of animals, 

 and the decay of dank vegetable and animal matter, is 

 taken up through the stomata of the leaves of plants, which 

 are in reality a part of their assimilative system, and 

 through the metabolism which goes on there, the oxygen is 

 liberated, and the carbon appropriated, in the elaboration of 

 the sap. Thus a balance is secured, and the purity of the 

 general atmosphere remains unimpaired. 



Decaying matters are always associated with the foster- 

 ing of germs, and the elimination of poisonous, foul-smell- 

 ing gases, the most deleterious of which is sulphuretted 

 hydrogen, easily recognisable by its characteristic odour of 

 putrid eggs. As we have already stated, however, the 

 quantity of carbonic acid in the air may be taken as a 

 reliable indicator of its purity or impurity. Wholesome 

 air ought not to contain more than about -06 per cent, 

 of carbonic acid ; the presence of 1 per cent, is harmful, 

 but when it reaches the proportion of about from 10 to 12 

 per cent., the air becomes absolutely )ioisonous. 



In virtue of the laws which regulate the diffusion of 

 gases, the carbonic acid and other gases given off as the 

 products of combustion tend to spread themselves through- 

 out the apartment, although, bulk for bulk, the carbon 

 dioxide is one and-a-half times as heavy as ordinary air. 

 Its distribution is further accelerated on account of its 

 greater temperature, for it usually leaves the body at about 

 98° Fahr., and the flame of a lamp at a considerably higher 

 temperature, wherebj' it tends to rise towards the ceiling. 

 The course of circulation is as follows : — On reaching the 



* " The Medical Annual." London, 1883-4, p. 119. 



