Oct. 13, 1882.1 



• KNOWLEDGE 



329 



Xow, — 

 log 28820-1= 

 log 182 G25= 



:5-4597000 

 :2-2G15602 



J log 8 =0-4515450 



fog 3141593=6-4971499 



7-7212602 

 substract 6 9486949 



6-948C949 



0-7725653=los 5-9233 

 This is still too small ; so that if we are right in con- 

 cluding from the ol)servation at Vienna on September 24, 

 that on that day at noon the comet had reached the position 

 shown at '/, Fig. 1, p. 327, the projection of which, Sm, on the 

 axis, jik; is about one-third of SD, then the period in which 

 the comet will return to perihelion is certainly less than 

 half a year. It is, however, to be noted that in that case 

 the orbit has been reduced in width (minor axis), so that 

 some such point as d' would be the true position of the 

 comet on September 24, the projection of which, Bin, on 

 kp is rather less than Sm. 



For my own part — so far as observations hitherto made 

 enable me to judge — I expect the comet back in less than 

 half a year. 



WHO DISCOVERED THE DIVISIOX I}T 

 SATURN'S RING r * 



EVERY one interested in the chronology of the discovery 

 of Saturnian detail mu^t thank you for your verbatim 

 extract from the " Philosophical Transactions " at large on 

 p. 307. My own quotation, on p. 295, was from the well- 

 known abridgment of the " Philosophical Transactions," 

 by Lowthorp, published in 1716, which is to be found in 

 so many libraries. Reading the original article now, in 

 extenso, it seems practically certain that your own inter- 

 pretation of Ball's meaning (foot-note, p. 294) must be the 

 correct one ; and that both he and Wallis (who was, pre- 

 sumal)ly, " the person to whom notice was sent hereof "), 

 regarded the " Notches or HoUownesses, as at A and B," 

 as evidence that there was a separate ring, or perhaps 

 two veritable ansa>, on each side of tlie body of the planet. 

 I have seen an engraving from a drawing by Huyghens, 

 in which this form of duplication is considerably exagge- 

 rated in comparison with that shown in the iiguro you 

 reproduce on p. 307. Certainly, if Ball had the slightest 

 notion that two concentric rings surrounded Saturn, it is 

 odd that he gave no indication of the division in his sketch. 



If the accompanying far-simUe of Cassini's sketch of the 

 planet, taken from Lowtliorp, be wortli reproduction, it 

 will show at once how unmistakably the French astro- 

 nomer saw the real interval separating the two rings, and, 



• A noto wliicli should liivvo iirrrodeil ttie title of tlio extract 

 referred to, was accidentuUy omitted. It iiiontioiiod tlint the 

 extract had been sent to us by Mr. J. Ward, and seemed entirely 

 to dispose of the claim made on Ball's behalf. Then the title 

 (which read rather strangely) should have followed in small 

 capitals, boinR really a sub-titlo only. We arn glad to notice that 

 a writer in tho Athenaum has followed Captain Noble's lead, and 

 seems on his way to tho same solution and conclusion. 



consequently, I would submit how truly he is entitled to 

 the entire credit of the discovery. " Ball's division " is 

 certainly a solecism, and should be banished from all future 

 astronomical works, as descriptive of the space separating 

 the two bright rings of Saturn. [Readers of the original 

 and new editions of my " Saturn and its System," please 

 notice this point : Cassini and not Ball discovered the 

 division in Saturn's ring.] William Xoble. 



OXYGEN AND DISEASE GERMS. 



MR. F. J. FAR.IDAY calls attention in the Times to 

 certain remarkable facts communicated by M. 

 Pasteur to the recent Hygienic Congress at Geneva. 

 Starting with the suggestion by Dr. William Roberts, 

 F.R.S., that disease germs might be "sports" from harm- 

 less saprophytes which had acquii-ed a parasitic habit, it 

 has been argued that such "sports" might be developed by 

 cultivation in the presence of noxious gases, or in confined 

 places in which the proportion of free oxygen present in 

 good air did not exist. The hypothesis has been specially 

 applied to the evolution of the tubercle bacillus, but it is 

 obvious that it is equally applicable to the evolution of the 

 germs of other diseases, such as typhoid fever. The pro- 

 cess described by M. Pasteur at Geneva, as having enabled 

 him to convert the virus of the form of typhoid fever which 

 caused great mortality among horses last year in Paris into 

 its own vaccine, has a noteworthy bearing upon this 

 hypothesis. M. Pasteur first tried to " attenuate " the 

 virus by cultivating the specific microbe, which he had 

 already discovered as associated with the disease, in 

 contact with air. But experiments showed that the 

 culture retained its fatal attributes for a certain period, 

 when it suddenly became absolutely sterile, or, in other 

 words, the microbe died. M. Pasteur then adopted a 

 method which can only be adequately described as a pro- 

 cess of nursing the microbe, so as gradually to adapt it to 

 a new mode of life, or, in other words, to modify it without 

 destroying its fertility. Taking a virulent culture from 

 the blood of a rabbit which, through inoculation, had died 

 of the disease, he sowed fresh portions of this culture in 

 veal broth on successive days, and kept the series in con- 

 tact with air. He had thus a graduated series of cultures 

 from virulent stock in process, each of these cultures 

 having been subjected to the modifying infiuence of oxygen 

 for a difl'erent period. M. Pasteur was thus able to seize 

 the moment when the culture which had been exposed 

 the longest to aeration became sterile, and to select a 

 culture on the eve of sterility, which he transferred to a 

 fresh infusion already found to be specially suitable to 

 the microbes, and which consisted of two parts of veal 

 brotli with one part of pure rabbit's blood. Having, in 

 fact, reduced the microbe to the verge of sterility, or death, 

 he subjected it at this critical moment to an invigorating 

 regimen, and thus protracted its vitjility and made it the 

 stock of a new serit-s of cultures. By repeating this pro- 

 cess again and again in all its details, M. Pasteur ultimately 

 evoheil a race capable of serving as the vaccine of the 

 origiiuil virus, oxygen having been the modifying influence 

 throughout 



There is a striking analogy between the treatment thus 

 described and that by means of which, about six years ago, 

 Friiulein Marie von Clmuvin evolved ambhjstoma, a land 

 salamandir, from the water-breathing ^lexican axolotL 

 She selected healthy animals, and first kept them in shallow 

 water, so that they were not quite covered by tlie water. 

 When their iiealth tleclined she restored them to deep 

 water. Gradually slie accustomed them to sliallow water, 



