September 15, 1923] 



NA TURE 



403 



convincing. Dante's cosmological ideas are so closely 

 interwoven with his great poem that it is easy enough 

 to find passages which illustrate it (see Nature, 

 vol. 107, p. 428). The author devotes more space 

 to meteorological phenomena, which are frequently 

 alluded to in the descriptions of the different localities 

 of the mountain of Purgator^^ but none of the quota- 

 tions given are of any special interest. 



Messrs. Baird and Tatlock have just issued their 

 " Standard Catalogue of Scientific Apparatus, 1923. 

 Vol. I. Chemistry." The previous edition of this 

 catalogue was published in 1914, and the outbreak of 

 the War a few months after publication rendered it 

 practically useless. The present edition is conceived 

 on a larger scale than the earlier one, the volume 

 before us — Chemistry — alone containing 954 pages 

 as against 1283 pages of the full 1914 catalogue. 

 Judging from this catalogue, manufacturers of chemi- 

 cal apparatus have fully recovered the paralysis 

 caused by the sudden stoppage of German goods in 

 19 14. Certain items are missing, such as German 

 balances, but every type of balance is to be found in 

 the list. Practically everything obtainable in 1914 

 can be purchased now, the only difference being that 



I instead of the major proportion coming from Germany, 

 most of the apparatus is manufactured in England. 

 Prices are naturally higher than in 1914, in round 

 figures, judging from the selection of a number of 

 typical pieces of apparatus, about double ; this may 

 be regarded as a normal ratio, and excludes the idea 

 of profiteering in this industry. Diligent search 

 revealed one item — india-rubber tubing — at less than 

 pre-War prices. Glass apparatus, now almost entirely 

 of British manufacture, shows some price anomalies. 

 Beakers are about 2-5 times pre-War, and heavy cast 

 glass about three times, probably due to difficulties in 

 manufacture ; on the other hand, blown glass appar- 

 atus is generally less than double pre-War price. For 

 example, an eight-bulb Young evaporator column is 

 only advanced from 27s. to 35s. The catalogue has a 

 good index, and reflects credit on the enterprise of 

 the publishers. 



The latest special catalogue of Mr. F. Edwards, 83 

 High Street, Marylebone, W.i, is No. 450, entitled 

 " Americana." It gives particulars of nearly 500 

 second-hand books relating to Central and South 

 America : geography and travel, books of views, 

 history, natural history, antiquities, etc. 



Our Astronomical Column. 



The Total Sola^r Eclipse of September 10. — 

 As we go to press (September 11) news reaches us 

 from the Royal Observatory, Greenwich, that the 

 solar corona was seen through slight cloud during 

 the total solar eclipse of Monday, September 10, and 

 that good photographs were obtained by Mr. Worth- 

 ington at Lompoc, California. 



Spectroscopic Parallaxes of Stars of Type B. 

 — The Astrophys. Journ. for June contains a paper 

 by W. S. Adams and A. H. Joy on this subject. 

 Their research was quite independent of that by D. L. 

 Edwards (Mon. Not. R.A.S., Nov. 1922) and is based 

 simply on general spectral type, not on differences of 

 intensity of particular lines. It has long been known 

 that there is less dispersion of absolute magnitude for 

 type B than for later types, and the authors adopt 

 definite values for each spectral sub-division. The 

 following is an abbreviated list of their adopted values: 



Adams and Joy prepared this list with the aid of 

 34 trigonometrical parallaxes and others derived 

 irom moving clusters, group motion, and various 

 statistical methods. 



A list then follows of the parallaxes of 300 stars, 

 based on these values. Their spectral types are 



deduced from Mt. Wilson spectrograms. The Harvard 

 types are given for comparison, and seldom differ by 

 more than one step. 



The later sub-divisions of tvpe O have also been 

 included, using H. H. Plaskett's notation of O5, Og, 

 O7, Ob, 64 for the stars with dark lines that precede 

 Bo in the sequence. The results have been tested by 

 plotting reduced proper motion against absolute 

 magnitude. The function actually plotted is o-2m + 

 log/i, ni being apparent magnitude and ^ proper 

 motion. The resulting graph is nearly a straight line, 

 which is claimed as support for their adopted values. 

 It is admitted that there are exceptional stars which 

 their formulae will not fit : on one hand, super- 

 giants, such as Rigel ; on the other, abnormally faint 

 B-stars such as Boss 15 17, for which Voute found the 

 trigonometrical parallax 0-074", while the spectro- 

 scopic one is 0-005". The authors hope that Mr. 

 Edwards's method may serve to find the dispersion 

 in parallax for each sub-type. 



Their largest spectroscopic parallax is 0-069* 

 (Boss 2698), and their smallest 0-002" (twelve stars 

 of about the 6th magnitude). 



SuNSPOT Activity. — There are signs of the begin- 

 ning of the new cycle of activity. A double spot of 

 appreciable size, followed by a train of small ones, 

 entered the disc shortly before the end of August, 

 and was seen near the west limb, flanked by a large 

 facula, on September 9. It was S. Latitude 29°, and 

 is the first high-latitude spot of considerable size in 

 the new cycle, though some very small sporadic ones 

 have been seen during the last year or more. 



On September 9 there was a second group of similar 

 type, but not quite so large, on the other side of the 

 equator, which entered the disc about September 5. 



The Mt. Wilson report had already noted that the 

 activity in June was greater than for some months 

 past, there being five days when two groups were on 

 the disc, and one day when three groups were visible. 



NO. 281 I, VOL. I 12] 



