198 



SCIENCE. 



[N. S. Vol. III. No. 58: 



known reason that all such distance measures 

 are often afifected witli systematic errors. It is 

 always a matter of personal opinion whether 

 measures of distance should be used in compu- 

 ting the orbit of a binary like 70 Ophivichi. 

 In any case, the curve which Dr. See draws to 

 illustrate the ' Perturbations in Distance ' can- 

 not be regarded as quite free from bias. Thus, 

 if we divide the observations into three equal 

 periods, we find : 



Period. Number of Points. 



Above See's Curve. Below See's Curve. 

 1830 to 1850, 15 5 



1850 to 1870, 13 7 



1870 to 1S90, 2 18 



It is evident that the curve needs raising at 

 one end and lowering at the other ; and if this 

 is done, it will come near admitting of a satis- 

 factory representation by means of a straight 

 line. However this may be, we wishto repeat 

 our former statement that this star is certainly 

 worthy of close attention from double-star ob- 

 servers. Dr. See's research serves to empha- 

 size this fact very strongly. 



In the Astronomical Journal of January 23 

 Dr. S. C. Chandlfer publishes a paper on 

 ' Standard systems of declination and proper 

 motion,' in which he comes to the conclusion 

 that "the system of the Fundamental-Catalog, 

 admirable as it was for its original purpose, has 

 now broken down, and the extension of its em- 

 ployment up to the present time, and certainly 

 for the future, should cease." Dr. Chandler 

 thinks that the proper system to use is that of 

 Boss. To prove this he compares the declina- 

 tions deduced by himself in a former paper from 

 mural circle observations at Greenwich between 

 the years 1825 and 1848 with the corresponding 

 declinations from Boss' catalogue and from 

 Auwers' Fundamental- Catalog. The agreement 

 with Boss is much better than that with Auwers, 

 especially after Boss has been corrected with a 

 small term for latitude variation. We are un- 

 able to see in these facts a sufficient justification 

 for Dr. Chandler's strong condemnation of 

 Auwers' system. The essential requisite of a 

 system of star places and proper motions is not 

 that it shall differ from the truth at all epochs 

 by the minimum amount. It is of no great con- 

 sequence if the difference from the truth be 



somewhat large for some epochs, but it is essen- 

 tial that such difference shall always admit of 

 being expressed as a function of the declination 

 without discontinuity. We believe that the 

 quantity of such discontinuity involved in the 

 use of Auwers' system is less on the average 

 than in the use of Boss' . Whether this be so or 

 not is at present a matter of individual opinion, 

 depending more or less upon the weight at- 

 tached to Bradley's observations. But there is 

 another practical essential of a star system which 

 is not at all satisfied by Boss' system. We refer 

 to the need of keeping the system up to date. 

 This has been done very carefully by Auwers, 

 but for Boss' system few of the later catalogues 

 have been treated. Thus it is practically im- 

 possible for an astronomer who wants to deduce 

 the best possible place of a star to employ the 

 recent accurate catalogues, if he wishes the 

 place referred to Boss' system. H. J. 



CHEMISTRY. 



LoBKY DE Bruyn has succeeded in preparing 

 hydrazine or diamide, NjH^, in pure condition 

 by treating the hydrochloric acid salt with 

 sodium ethylate and distilling. The compound 

 crystallizes at low temperatures, and can be 

 boiled under the atmospheric pressure without 

 decomposition. Attempts were made to pre- 

 pare diimide, NjHj, by treating hydrazine 

 with iodine, but these were without success. 



Recent experiments by Gr^haut show that 

 the effect of acetyline upon the animal system 

 is very slight. If it unites with the haemoglobin 

 of the blood at all, the compound is very un- 

 stable, and not to be compared with the com- 

 pound of hfcmoglobin with carbonic oxide. 

 This fact is of special interest in view of the 

 probable extensive introduction of acetyline for 

 illuminating purposes. 



general. 

 At the meeting of the Paris Academy of Sci- 

 ences on January 6th M. Marey was succeeded 

 in the presidency by M. A. Cornu, and M. 

 Chatin, the botanist, was elected Vice-President 

 in the place of M. Cornu. At the meeting on 

 January 13th M. Marcel Bertran was elected a 

 member of the section of mineralogy, succeeding 

 Pasteur. 



