SCIENCE-GOSSIP. 



101 



darkened glass chamber, free from dust, disappears, 

 but returns again if dust be admitted. We say 

 that a ray of sunlight breaking into a darkened 

 room shows us the myriads of motes dancing in its 

 beam, but the more correct statement would be 

 that the motes show us the track of the sunlight. 

 The character of our sunset and sunrise effects is 

 determined by the same cause, the more dust the 

 warmer and softer the light, so that to view these 

 phenomena from mountain tops, where dust is 

 scanty, is a mistake, at any rate as far as regards 

 effects of colour. 



Another great work in which dust is quietly 

 engaged is the shifting of soil. We can see this 

 on a small scale on every country walk. The fields 

 bordering a great highway are constantly receiving 

 a powdery layer, insignificant in itself, but sufficient 

 in the course of years to materially raise the level 

 of the surface and to bury objects lying on it. In 

 countries where sand and dust storms are of 

 common occurrence the process is much more 

 speedy, a single storm sufficing to obliterate the 

 landmarks of a whole country-side. It was held 

 by many that the gorgeous sunsets seen in this 

 country during the autumn of 1SS3 were occasioned 

 by the dust following the eruption of the far- 

 distant Mount Krakatoa. A similar dust-cloud 

 buried the city of Pompeii in three days 



Passing to another part of the subject, consider 

 for a moment the composition of dust. Speaking 

 generally, it consists of animal and vegetable 

 matter, and it is upon these two constituents that 

 the myriads of germs which surround us flourish ; 

 consequently a dusty atmosphere means a germ- 

 laden atmosphere. Dirt, on the other hand, affords 

 a far less favourable breeding-ground for germs. 

 It is too, to a great extent, fixed, so that although 

 during a life-time one may have to swallow a peck 

 of dirt, it is still more certain that one must 

 breathe a ton of dust. On the whole it would 

 seem better to be dirty than to be dusty. 



I>ust is the great carrier of micro-organisms, the 

 re inseparable. The number of microbes 

 found in a given sample of air will vary according 

 to the place from which it is taken. For instance, 

 a cubic yard of air taken at the top of a Swiss 

 mountain was found to contain, on the average, 

 one genu: a similar quantity taken in the mid- 

 Atlantic, six germs ; in a city park, 450 ; in a city 

 street, 4,000; and in a house, 10,000 germ 1 

 dustiest spots yielding the highest numbers of 

 organisms. 



ive, then, in an atmosphere containing 

 200 microbes per foot, and thirty millions of 

 dost particles per inch, and it is well to consider 

 what evils we suffer as the natural consequence. 

 The du it laden air of mine-, and Hour-mill . will, if 

 :. give riv: to the mo<vt terrific and disastrous 

 • eicesnive mortality amongst cut- 



lers, potters, and cotton workers is but the result 

 of breathing air laden with fragments of the 

 materials operated upon. These effects are now 

 sufficiently obvious, and measures are taken to 

 remedy them ; but the evils arising from dusty 

 streets and dusty houses are but little appreciated. 

 With regard to our streets it cannot too strongly 

 be emphasized that their efficient watering is a 

 hygienic measure of the first importance. The 

 mechanical irritation set up by breathing a dusty 

 atmosphere may be sufficient to excite various lung 

 diseases, whilst the accompanying germs may 

 inoculate us with their several disorders. The 

 fearful eye diseases so prevalent in Egypt and 

 the East are consequent upon the clouds of 

 filth that rise from the unwatered roadways, and 

 the winter epidemic of pneumonia which visits 

 Johannesburg is attributed to the same cause. 

 The part played by dust in the formation of fog, 

 mist and cloud has already been referred to, and 

 it must be remembered that even when these are 

 absent a pall of smoke hangs over our towns, so 

 that we seldom or never get our due allowance 

 of light and sunshine, which are as essential to 

 our well-being as to that of every tree or flower. 

 The dust from our chimneys and houses deposits 

 on everything : it is an enemy to cleanliness, 

 and it renders our climate cold and sunless. 

 The most powerful of all germicides is sunshine ; 

 and by daily contributing, as we do, to the 

 volume of smoke and dust, we are rendering 

 our homes unhealthy and our lives less bright and 

 cheerful. 



Let it be remembered we ourselves are directly 

 responsible for the condition of the atmosphere. 

 Look for a moment at the conditions of town-life 

 to-day. The streets, except indeed they be of wood 

 or asphalt, are one day pools of mud and the next 

 may produce clouds of dust. A goodly proportion 

 of our fuel is scattered broadcast into the air in the 

 form of smoke from factory or domestic chimneys. 

 Every detail of our houses is either calculated to 

 create dust or would seem to be especially con- 

 structed to retain it. Our floors are rows of chinks, 

 choked with dust, held together by a few boards. 

 Our ceilings are embellished with cornices — 

 elaborate dust-traps only cleansed at the triennial 

 whitewashing ; fluffy wall-papers, carpets, curtains, 

 each of the thousand and one bits of drapery 

 with which we ornament our rooms, contribute 

 their share to the general dust cloud. We are 

 ever manufacturing dust-traps. The junction 

 of walls with ceiling and floor are angles nevei 

 to be explored. We nail down our carpets, so 

 that even an annual beating becomes a labour. 

 The very design of our furniture is a snare, so 

 that few of us care to thinl. "I tli<- du 1 honor 



that lie bidden In the Bat, excavated tops of 

 ti and book-cases There are, of course, 



