February i6, 191 i] 



NATURE 



523 



Hpyond all question the structural formula of camphor, 

 lat the confirmation now given of the validity of the 

 \nthesis is of considerable value and importance. 



An article on petrol-engine ratings appears in Etigineer- 

 >ig for February lo. It has never been altogether clear 

 \ hy so much ingenuity has been expended in the invention 

 i>f formulae which will give the horse-power of a petrol 

 . ngine in terms of its physical dimensions, especially as 

 most builders of such engines are quite prepared to state 

 the actual brake-horse-power which has been given by any 

 of their engines. In 1906 the Royal Automobile Club 

 settled on the well-known formula B.H.P. =o-4D^N. This 

 formula is founded on an assumed mean effective pressure 

 of 67-2 lb. per square inch and a piston speed of 1000 feet 

 per minute. A report was presented at the meeting of the 

 Incorporated Institution of Automobile Engineers on 

 February 8, drawn up by the horse-power-formula com- 

 mittee. A new formula is given which avoids the objec- 

 tions raised to that given above, viz. the assumption of 

 values for both the mean pressure and the piston speed, 

 and the form being such that no correction can be applied 

 for the increase of mean pressure which takes place with 

 increase in the diameter of the cylinders, or for the 

 increase in piston s{)eed which occurs with an increased 

 stroke-bore ratio. The committee's formula is based on 

 the results of tests on 144 actual engines, and is as 

 follows : — 



B.H.P. = o-45(d + s)(d-i.i8)N, 



where d is the bore of the cylinder in inches, s the stroke 

 of the piston in inches, and N is the number of cylinders. 



We are informed that, owing to an alteration in the 

 publications, papers read before the Physical Society of 

 London in future will appear, in general, only in the Pro- 

 ceedings of the society, and not in the Philosophical 

 Magasine. The Proceedings and other publications are 

 now obtainable by the public from the publishers to the 

 society, The Electrician Printing and Publishing Company, 

 Ltd., I, 2, and 3 Salisburv Court, Fleet Street, London, 

 E.C. 



The eighteenth report of the Leicester Museum and Art 

 Gallery Committee to the Town Council for the year 

 ended March 31, 19 10, has been received. The long- 

 projected extension and reconstruction of the museum and 

 art gallery buildings have now been commenced. 

 Important additions were made to the museum during the 

 j'ear ; in the department of Coleoptera and economic 

 entomology, a collection of 6000 sf>ecimens of 1300 species 

 was presented by Mr. C. B. Headly, and 40S specimens of 

 356 species, chiefly from Leicestershire, were given by Mr. 

 F. Bouskell. 



OUR ASTRONOMICAL COLUMN. 



Nova Lacert.^;. — Several further notes on Nova Lacertae 

 ^>pear in the Astronomische Xachrichten. In No. 4470 

 Prof. Pickering gives particulars concerning the earlier 

 history of the star, according to the Harvard collection of 

 photographs, and states that spectrum photographs by Mr. 

 E. S. King showed eleven bright lines. Prof. Nijland 

 gives the results of magnitude observations at Utrecht 

 showing a gradual decrease in the nova's brightness from 

 7*40 on January i and 2 to 8-30 on January 16; the colour 

 was fairly constant at 3-7, and is found to be similar to 

 that of the long-period variables R Arietis, T Cassiopeiae, 

 and S Ursae Maj. at their maxima. Photographic 

 magnitude observations at Munich, reported by Dr. Kiihl, 

 agree with the above in showing a somewhat similar 

 decrease over the same period 



In No. 4471 Dr. Max Wolf gives the measures of the 

 nova's position on plates taken on January 17 and in 1904, 

 and raises the question whether the slight difference of 

 oios. in R.A. may be ascribed to proper motion. 



NO. 2155, VOL. 85] 



Mr. P. M. Ryves has communicated to us his observa- 

 tions of the nova's magnitude, made at Zaragoza, Spain^- 

 between January 5 and February 5. The observations 

 were made with a 3-inch telescope, Harvard and D.M. 

 magnitudes being taken for the comparison stars, and 

 show a steady decrease from 72 to 8-6 in the observed 

 magnitudes. 



A further note concerning the spectrum of the nova, as 

 photographed at the Meudon Observatory, is contributed 

 by M. Idrac to the Comptes rendus for February 6. Three 

 fine nights, January 28-31, permitted him to secure photo- 

 graphs with from one to three hours' exposure on pan- 

 chromatic plates. The very broad, bright hydrogen lines 

 are seen to be divided into two components, of which the- 

 brighter show a " shift " of 7 .-Vngstroms towards the 

 red, while the fainter are displaced 16 Angstroms towards 

 the violet ; a dark line, possibly double, occurs on the 

 violet side of H7. In the jellow there are three bright 

 bands, at about X 587-4 (probably helium, 587-6), \ 575-4, 

 and A 567-5, while the green shows a band, about 30- 

 Angstroms broad, having its centre near X 500, and a 

 bright line at A 493-7. The band at A 465, mentioned in 

 the earlier communication, is shown to be multiple, having^ 

 maxima at A 462 and A 466, with a fainter component at 

 A 470 ; the bright lines near A 437-4 and A 458-3 are also 

 shown, but appear less marked than previously- Other 

 maxima and minima mark the continuous spectrum, and 

 are probably indicative of lines or bands beyond the 

 separating power of the spectr<^raph ; such maxima are 

 well marked in the neighbourhood of A 425 and A 445. 

 The presence of nebula lines in the spectrum is open to- 

 question, but the strong band near A 500 suggests the 

 possible presence of the chief nebula line ; its great width, 

 however, prevents any definite solution of the question ; iir 

 fact, all the wave-lengths given may only be accepted as 

 approximations. 



Ephemeris for Faye's Comet. — To No. 4469 of the- 

 Astronomische Nachrichten Dr. Ebell contributes a daily 

 ephemeris for Faye's comet, based on the elements pub- 

 lished in No. 187 of the Lick Observatory Bulletins, and 

 extending to March 27. At present the object is very near 

 to ir' Orionis, and is calculated to be a little fainter than 

 the thirteenth magnitude ; its motion is easterly, with a 

 slight northern trend. 



Standard Astrometrv. — An important suggestion as to 

 the publication of results obtained in accordance with the 

 scheme of the International Astrographic Conference is- 

 made by Mr. W. E.- Cooke in No. 4470 of the Astro- ■ 

 nomische Xachrichten. This scheme embodies the observa-' 

 tion of a definite list of fundamental stars by observatories- 

 equipped to carry out such work with the greatest possible 

 accuracy. Other stars, etoiles de repere, will be con- 

 nected with these by careful differential obsenations 

 through a third set of stars employed as " intermediate- 

 standards." Mr. Cooke's suggestion is that while ihe- 

 differential observations should be made with the greatest 

 possible accuracy, the results should be published in such ' 

 a manner as to show the standards upon which each- 

 catalogued position depends. 



The value of the suggestion is obvious. Although the- 

 international fundamental catalogue will probably be far 

 superior to any now existing, future improvements in the 

 standards are inevitable, and if Mr. Cooke's plan is 

 followed, future observers will be able to reduce the 

 individual published observations to the improved" 

 standards. 



Mr. Cooke has followed this plan in vol. iv. of the 

 Perth Observatory Meridian Observations, 31° to 33° S. 

 (1900), recently received, and in an appendix he gives- 

 blank columns in which the corrections, dependent upoir 

 the future improvement of the places given in the " Perth" 

 Catalogue of Standard Stars, 1905-0," can readily be 

 inserted. ' 



New Spectroscopic Binaries. — Lick Bulletin No. 182 

 gives the measures of a number of stars of which the 

 radial velocities have recently been discovered to be-' 

 variable. The following were discovered on plates secured 

 at Santiago, generally with the two-prism instrument, and" 

 are described by Mr. J. H. Moore : — A Hydri, y Mensae, 

 { Columbae, h^ and h^ Puppis, 5 Antliae, 0^ Crucis, 4 " and 

 h Centauri, and d Lupi ; for h Centauri Mr. Paddock finds 

 a period of about 16-7 days. Observations made during^' 



