Dec. 1, 1882.] 



• KNOW^LEDGE • 



433 



HAS THE MOOX AN ATMOSPHERE ? 



I AM aware of the logical weakness of all merely nega- 

 tive e\-idence, cumulative though it may be ; but I 

 may, perhaps, be permitted to adduce my own ven,- exten- 

 sive experience in the observation of occultations of stars 

 and planets by the moon, as tending to show that no lunar 

 atmosphere of any appreciable density exists. If physicists 

 are content to dignify with the name of atmosphere a con- 

 dition of things cognate with that which we call a 

 "vacuum " in a good air-pump, I have nothing more to say. 

 If, however, by atmosphere it is intended to signify any 

 envelope, akin in density even to the upper regions of that 

 surrounding our own globe, then would I say that to 

 me the moon has always seemed airless. Now I have seen 

 stars disappear behind all parts of her limb, both illumi- 

 nated and unilluminated, elevated and depressed, rugged 

 and plain, and a more absolutely instantaneous phenomenon 

 I am unacquainted with. I have even seen a star disappear 

 and reappear among the mountains and valleys on the 

 serrated edge of the moon, but without the faintest indica- 

 tions of distortion or diminution of light I was, though, 

 never so impressed with the idea of a total absence of any 

 lunar atmosphere as I was on the occasion of the occulta- 

 tion of Saturn by the moon on the night of ilay 8, 1S59, 

 of which an account will be found in pp. 2i2 and 243 of 

 Vol. XIX. of the Royal Astronomical Society's " Monthly 

 Notices." The detinition was remarkably fine, and with a 

 power of 2.5-5 the whole of the detail of the planet was seen 

 in a style suggestive of the engravings in works on astro- 

 nomy. Now all this detail, both of immersion and emersion, 

 was sharply visible up to the very limb of the moon. With 

 my eye and the power I employed, I am convinced that I 

 could not have missed any phenomenon having its origin in 

 refraction to the extent of 1". Nothing of the sort, though, 

 was visible. 



I must in candour, however, add that on two separate 

 occasions when I have been observing partial solar 

 eclipses I hare noted an appearance which would seem to 

 lend some colour to the theory that an atmosphere of con- 

 siderable tenuity does surround our satellite. This appear- 

 ance took the form of two exceedingly small thorns, as it 

 were, of light, at the extremities of the solar cusps, sug 

 gesting the idea of the sun's limb turning verij slightly 

 outwards at these points. The first time I saw this was on 



September 28-29, 1875, when it was also witnessed by my 

 wife and Mr. J. Lister Godlee, of the Equity Bar. Neither 

 of them had any experience in observing, but each saw 

 these little points at once, on viewing the eclipsed sun. 

 The accompanying illustration of this, drawn at the tele- 

 scope, is copied from the R.AS. MonMy Noticcn, Vol. 



XXXVI., p. 41. I witnessed a repetition of this curious 

 efiect on May 17 last, and it may be interesting to put on 

 record here that, having viewed it with an ordinary 

 diagonal solar eye-piece, I removed this, and substituting a 

 plain Huyghenean one, projected the image of the sun on 

 to a screen, under wliich circumstances the " thorns " were 

 just as visible as ever. William Noble. 



HrxTixG Alligators. — J. Russell, a son of Major 

 Russell, famous during the Florida War, now makes a pre- 

 carious living in South Florida as a guide to visiting 

 sportsmen. For a bonus of two dollars he ^vill dive into 

 the current of the muddy St. John and bring up an 

 alligator. He actually brings them out of their holes. 

 Strange as this may seem, it is the only safe way to ap- 

 proach an alligator. They dig holes in the river-banks, 

 just below the surface of the water and crawl into them. 

 .Tim dives down, crawls in rapidly, and seizes the saurian 

 by the tail, who, startled, immediately backs out. Jim 

 holds on, keeping his legs stiff till clear of the bank, 

 when he darts away, and the alligator, rising to the surface 

 for an instant to see what is the matter, is slam by waiting 

 gunners in a boat. This has become common sport on the 

 Tipper St. John River. 



The Diffusigx of Bacteria. — The researches of M. 

 Pasteur and Darwin have shown how earthworms may aid 

 the diffusion of small organisms, some of which may 

 produce disease. Professor Schnetzler states that the 

 dejections of earthworms always contain numerous 

 Uving bacteria and their germs (the hay-bacterium in- 

 cluded). It is clear that bacteria in enormous quantity 

 float in the air about us ; and we have at easy command, 

 Professor Schnetzler points out, a small apparatus 

 traversed by about 8,000 cubic centimetres of air per 

 minute, which may inform us as to those floating germs. 

 This is no other than the nasal ca-vity, on the mucous 

 surface of which air-particles are deposited. To observe 

 these he advises injecting the nose with distilled water 

 (completely sterilised) by means of a glass syringe 

 pre-s-iously calcined. The liquid so obtained is put in one 

 perfectly clean watch-glass, and covered by another. With 

 a microscope magnifying 700 or 800 one finds, among 

 various particles in the liquid, some real live bacteria. If 

 the liquid be kept a few days in a clean glass tube hermeti- 

 cally sealed, the bacteria are found to have increased very 

 considerably. One sees Bacterium lermo, vibrio, .^piriUum 

 bacillus snbtilis, even some infusoria, and spores and frag- 

 ments of fungi Professor Schnetzler has further success- 

 fully cultivated the organised germs by means of a mixture 

 of gelatine and distilled water. Why do not those bacteria 

 in the nasal cavity always multiply and develope and pene- 

 trate to the windpipe and lungs I Their progress is, doubt- 

 less, opposed by the vibratory movements of cilia (or minute 

 hairs) in the air-passages, and the weakly alkaline reaction 

 of the nasal mucus may (it is also suggested) be unfavour- 

 able to some of them. Cohn has proved that bacteria 

 producing acid fermentation perish in liquids with alkaline 

 reaction. Infectious bacteria may, however, multiply to a 

 formidable extent on living mucous surfaces, witness the 

 growth of the micrococcus of diphtheria, brought by the 

 air into the air-passages; also the bacterium of anthrax. 

 The bdcilhts of tubercle, as Koch has lately shown, may be 

 transmitted from one person to another by the air-passages. 

 Professor Sclinetzler thinks hay fever may also be due to 

 bacteria entering the nose. While the development of 

 bacteria on normal mucous surfaces is usually limited, 

 millions of them are found in the dejections of healthy 

 children. 



