August. 1913. 



KNOWLEDGE. 



293 



the properties of spirit more clearly than heretofore, 

 and we call the matter "living" because we recognise 

 the kinship between its spirit and that which we call 

 " ourselves." The raisoti d'etre and purpose of the 

 whole process is, I believe, the differentiation of homo- 

 geneous spirit into individual, self-conscious units 

 or souls capable of true happiness — the one thing of 

 absolute value. This is only perfectly achieved in 

 man. Of course, a theory so wide and comprehen- 

 sive as this deserves more than the bald statement 

 here alone possible. I have attempted a fuller state- 



ment, though very inadequately, in the essay already 

 referred to ; and I must also refer the reader to the 

 remarkable metaphysical treatise of the Swedish 

 philosopher, Swedenborg, entitled " The Divine Love 

 and Wisdom," which is the chief source of these 

 views concerning the ultimate significance and 

 nature of life. My primary reason for calling 

 attention to the theory here is to indicate how 

 entirely it fits in with the doctrine of evolution and 

 the latest scientific view concerning the possibility 

 of the spontaneous generation of life. 



CORRESPONDENCE. 



THE NUMBER OF "DOUBLE" STARS. 

 To the Editors of " Knowledge." 



Sirs, — In your number for June, on page 239, Mr. E. Holmes 

 criticises a correct statement of the late Mr. F. W. Henkel as 

 to the number of known double stars. The words he quotes 

 are : Perhaps as many as twelve thousand such couples are 

 known." I take exception to his criticism ; the most correct 

 word of these ten is perhaps. Further, the expression 

 standard authority " is out of place ; there is no one 

 standard authority. Let me explain. The branch of 

 astronomy known as "double stars" (two stars in close 

 juxtaposition as viewed from the earth) has become very 

 expansive since I commenced observing double stars in 1881 ; 

 the great increase in the optical power of recent telescopes 

 has brought thousands of optical pairs of stars upon record. 

 The chief merit of these modern observations is that they 

 are made with the finest instruments and most skilled 

 observers in this branch ; many of these observations 

 are duly recorded in Mr. Burnham's " Magnum Opus," in 

 1170 pages, and the total number of double stars which he 

 gives therein is thirteen thousand six hundred and sixty-five 

 (not fifty-five, as given by Mr. Holmes). This work was 

 published in 1906 by the Carnegie Institution of Washington. 



But of what does this consist ? I opened this catalogue at 

 random and it happened to be page 112 ; this is what is there 

 (with thirty-three properly observed pairs) : — 



Upon referring to Vol. II (notes) I find there is no further 

 information given to Nos. 5568, 5577, 5578, 5596, 5602, 5612 ; 

 to Nos. 5564, 5575, 5587, 5593, 5611 there are recent and 

 accurate measures given ; therefore the Herschel approxima- 

 tions might have been abandoned and not again, reprinted. 

 They are already in Smyth's " Celestial Cycle " and Gledhill's " 

 Handbook" ; Nos. 5588, 5589, 5601, 5607, 5609, and 5610 have 

 notes, and there seems no need to have again numbered them, 

 nor to have included them in a good reference catalogue, except 

 among the notes or in a table in the Introduction. 



The general result is that on page 112 there are fifty pairs 

 of stars : of these, seventeen are as just quoted in detail, none 

 of which should have so appeared in an accurate and up-to- 

 date catalogue, except as mere notes. The whole volume is 

 similar to this, and the 13,665 pairs or double stars may be 

 safely reduced by at least twenty-five per centum, and we get 

 about nine thousand pairs worthy of inclusion in the tabular 

 catalogue : the R.A.'s and Declinations are given for an old 

 epoch (1880). Then this only includes stars to minus thirty- 

 one degrees ; none of Innes's valuable work, or of other 

 southern observers, is included. So Mr. Henkel's "perhaps 

 as many as twelve thousand such couples are known " is a 

 statement not very far from the correct number at present 

 published, mere estimations omitted. From Mr. Holmes's 

 reference to other catalogues of double stars one is lead to 

 believe that he is unacquainted with the contents of that 

 excellent catalogue by Mr. T. Lewis, published also in 1906. 

 While the catalogue of Mr. Burnham is collected from all or 

 many sources since 1780, and is still far from complete or 

 homogeneous in character — though a work of reference so far 

 as it goes — that by Mr. Lewis is formed upon a definition 

 plan, being based upon a systematic series of observations of 

 about three thousand double stars by W. Struve, with which 

 have been incorporated in detail all known and good observa- 

 tions until about 1904. Much valuable information upon the 

 orbits of the more interesting binary stars is given — as also 

 in Mr. Burnham's catalogue. So it may be truly called a 

 standard work of reference for W. Struve's stars, and it will 

 be used for many a year ; it does not touch those modern 

 pairs of bright stars with very faint stars within about 1", 

 observed with instruments of 25-in. to 40-in. object glasses. So 

 much for the visual pairs, few of which are " binaries." 



What of the spectroscopic binaries, which are of the 

 greatest interest ? Their known number is already consider- 

 able. None of these are as yet thought to be worthy of 

 inclusion in a so-called standard catalogue of " double stars." 

 Mere numbers will not make a standard catalogue ; uniform 

 quality, completeness, and up-to-date epoch and material is 

 what we should expect. 



Oxford. f. A. BELLAMY. 



P.S. — I should like to mention that this letter was written 

 quite in ignorance of Mr. Henkel's death, and it was in type 

 before I was informed of it. 



