136 



THE POPULAR SCIENCE MONTHLY. 



Dr. Hartwig's observation, by several other 

 observers, and has now become an object 

 of interest and attention to every one who 

 possesses a tele:?cope. The first observation 

 of it appears to have been by Jlr. Isaac W. 

 Ward, of Dunecht, on August I'Jth. It was 

 not visible at Brussels at the beginning of 

 August ; and the Rev. S. II. Saxby, care- 

 fully observing the nebula on the 6th, 9th, 

 and 10th of the month at Davos Platz, saw 

 no sign of a stellar nucleus. The telescope 

 at Dunecht on the 5th of September showed 

 it as a star of the 7J magnitude, with a 

 continuous spectrum. At the Greenwich 

 Observatory, on the 4th of September, its 

 spectrum was shown to be of precisely the 

 same character as that of the nebula, or per- 

 fectly continuous, with no lines, either bright 

 or dark, visible, and the red end wanting. 

 It therefore presents no evidence of an out- 

 burst of heated gas, such as was the case with 

 the " temporary " stars T. Corona in 1866 

 and "Nova" Cygni in 1876. The appear- 

 ance of new or temporary stars, though an 

 event that must always excite remark, is not 

 really unusual. One appeared in May, 1859, 

 in the nebula or cluster 80 Mersier, and 

 shone with a magnitude diminishing from 

 the 7th till the 10th of June, when it van- 

 ished, and has never been seen since. A 

 similar star was discovered in a nebula in 

 the Unicom in 1861, and is now ranked as 

 a variable star, R. Monocerotis. The star 

 Eta Argus, in the "key-hole nebula" in 

 Argo, is also a variable star, whose appear- 

 ance at its brighter stages might suggest 

 to superficial observation the idea of a new 

 or temporary star. It remains to be ascer- 

 tained whether the present star really be- 

 longs to the nebula or is an outsider pass- 

 ing over the line of vision between us and 

 it. Spectroscopic and photometric observa- 

 tions, so far as they have gone, indicate a 

 constitution identical with that of the neb- 

 ula, but they are not complete. If it does 

 belong to the nebula, a fact mentioned by 

 Mr. R. A. Proctor becomes very important. 

 Mr. Spencer has pointed out that no nebu- 

 la which could be resolved into stars could 

 possibly lie outside the limits of the galaxy 

 or of the great system of which our solar 

 system is a member ; for the outer edges of 

 that system are so far irresolvable. It was 

 generally agreed that, if any nebula lay out- 



side of the system, it was this one in Andro- 

 meda. Now, if a star is distinguished in 

 this body, it is clear also that it too must 

 lie within our system. 



Shall we raise Silk at a Loss ?— In 



the discussion of a paper by Dr. Riley, in the 

 American Association, advocating tariff " en- 

 couragement " of silk-culture in the United 

 States, Mr. Edward Atkinson remarked that 

 the project is not desirable. There is no 

 lack of employment for labor in the United 

 States, as the high rate of wages shows ; 

 and the fact that the making of reeled silk 

 has been unprofitable shows that capital 

 can be better employed. Silk-culture is a 

 handicraft simply, and has been carried on 

 by the poorest and most inefficient peoples, 

 who, as they rise in the scale, abandon it, 

 as is now coming to be the case in Southern 

 France. The argument that we shall save 

 the $20,000,000 which we now pay for 

 imported silk is fallacious. When we ex- 

 change articles produced b)' labor costing 

 one dollar per day, for the silk of China or 

 Japan raised by labor costing five or ten 

 cents a day we gain and not lose. We can 

 not afford to do for ourselves what pauper 

 laborers will do for us cheaper. 



Chemistry at the American Association. 



— The Chemical Section of the Association 

 was opened witii an address by Professor W. 

 R. Nichols, of the Massachusetts Institute 

 of Technology, on " Chemistry in the Serv- 

 ice of Public Health." The author showed 

 that chemistry has an educational oflice to 

 fill in the service of sanitary science, in 

 teaching the public what its capabilities 

 and limitations are, and correcting the er- 

 roneous ideas that are entertained as to the 

 nature of certain processes in preparing 

 food-substances, and the effect in them of 

 the application of particular reagents. Re- 

 specting two subjects now much talked of 

 in sanitary circles. Professor Nichols said : 

 " Microbes may well be left to the biolo- 

 gists, and possibly sewer-gas as well, since 

 chemists have failed to discover any sub- 

 stances in the gas which could produce the 

 well-known ill effects. . . . It is asserted by 

 some that the day of chemical examinations 

 is passing away, and that the wholesomcness 

 of water will be determined by the biologist, 



