270 



NATURE 



[Feb. 4, 1875 



" Uranometria," but we find it in the catalogue to Heis's 

 Atlas as a 67. In the excellent chart of the seventh hour 

 of R.A., by FcUiicker of Kremsmunstcr, forming one of the 

 series prepared under the auspices of the Berlin Academy 

 of Sciences, we find it marked only of 8-9 magnitude. 

 There is consequently sufficient evidence upon record to 

 justify the appearance of this star in our cataloguesof 

 suspected variables, even if it be not considered decisive 

 as to variability. Yet the object seems to have been 

 generally overlooked of late years. We are nevertheless 

 able to state that in 1873 and 1874 small fluctuations of 

 brightness could be detected, and may recommend it to 

 the attention of observers who are more especially inte- 

 rested in the variable stars. The position for the com- 

 mencement of the present year is in right ascension, 

 7h. 23m. OS., and polar distance, 91° 39'. A star of g'lo 

 magnitude precedes it about 4 seconds in R.A., and 

 about i' north. The colour is a full yellow or light 

 orange. 



(2). Mira Ceti, according to the formula of sines in the 

 last catalogue of variable stars, issued by Prof. Schonfeld, 

 will attain its maximum in the present year on February 

 24. The minimum determined in the manner adopted 

 by this eminent authority will fall on September 30. The 

 first maximum of 1S76 is on January 17. 



(3), /3 Cygni was indicated as variable by J. Klein, of 

 Cologne, from a series of careful observations by himself, 

 between July 1S62 and November 1S63, and Schonfeld 

 includes the star in a provisional list prefixed to his cata- 

 logue of 1875, ascribing a variation between 33 and 3'9 

 mag. to the brighter component of this beautiful object. 

 It is not the first time that variability has been suspected 

 in one component only of a double star. We are able to 

 state that last August, fi Cygni, as a naked-eye object, 

 certainly looked dimmer than we had often remarked it. 



The Zodiacal Light has presented itself on each 

 clear evening since our last, but most conspicuously on 

 the 31st ult. It was then distinctly traceable to it Arietis, 

 and at best views a fainter offset appeared to extend very 

 nearly to the Pleiades. The axis passed a few degrees 

 south of X Piscium. The intensity of light was certainly 

 more than twice that of the Galaxy in its brightest part 

 between the constellations Cassiopea and Cygnus. 



Encke's Comet. — The re-discovery of this body is not 

 yet announced, but it will be strange if it is not detected 

 with the larger telescopes before moonlight interferes in 

 the evening. In 1842, when the perihelion passage 

 occurred at the same time as in the present year, it was 

 observed with the Berlin 9-inch refractor on Feb. Sth ; 

 much more effective instruments, however, are now com- 

 mon, and if the comet's constitution has remained un- 

 changed, we might have expected observations in 

 January. 



Hallev's Comet.— In our "Astronomical Column," 

 next week, we shall give the principal results of the late 

 M. de Ponticoulant's calculation of the perturbations of 

 this comet (so interesting, especially to English astro- 

 nomers) during the actual revolution, and describe the 

 path in the heavens which his work indicates for the 

 year 19 10. 



ANNUAL REPORT OF THE ]VARDEN OF 



THE STANDARDS 



'T'HERE has been just issued by the Queen's printers 



-'■ the Eighth Annual Report of the Warden of the 

 Standards, Air. H. W. Chisholm, on the proceedings and 

 business of the Standards Department of the Board of 

 Trade. 



When we remind our readers that the Standards de- 

 posited in that department have been the result of the 

 labours of many men of science, including Davies Gilbert, 



Wollaston, T. Young, Kater, Daily, Sir J. Herschel, Earl 

 of Rosse, Lord Wrottesley, Sir E. Sabine, and lastly, but 

 most of all, W. H. Miller and the present Astronomer 

 Royal, we need scarcely say there should be much in this 

 Annual Report worthy of our notice. We confine our 

 notice here to that part of the business of this department 

 which is most likely to interest our readers, without re- 

 ferring to its various official or State duties. 



One part of the business of this department appears 

 to be the conducting of comparisons and other operations 

 with standards of length, weight, or capacity, in aid of 

 scientific researches or otherwise. Amongst such com- 

 parisons we note the determination of the lengths of two 

 Russian pendulums for use in the Great Trigonometrical 

 Survey of India, in ascertaining by combined astro- 

 nomical and telegraphic observations the exact position 

 of a number of fixed points on the earth's surface. 

 Standards were also verified for the Governments of 

 Canada and India, for special use. 



Chemists and physicists are glad to rely on the accuracy 

 of their measures or weights, as compared with our own 

 or foreign standards, and to be assured of the constancy 

 of the units employed in their researches. This part of 

 the business of the Standards Department would appear 

 therefore to be of practical use to those whose researches 

 require such accuracy. To maintain uniform the weights 

 and measures of our laboratories is not only aiding indi- 

 vidual research, but facilitating the exchange of scientific 

 experience. 



Many additional instruments are stated to have been 

 added to the valuable collection of comparing apparatus 

 deposited in this department : one of these is the new 

 powerful air-pump, by Deleuil, to be attached to a vacuum 

 balance. During the preparation of new gold and silver 

 standard trial-plates, elaborate experiments were made by 

 the chemist of the Royal Mint, on gold and silver alloys, 

 reference to which is made in the special Report of 

 the Warden of the Standards appended to the Report. 

 These experiments are referred to more particularly 

 in the paper by J. Norman Lockyer, F.R.S., and W. 

 Chandler Roberts, read before the Royal Society on 

 Nov. 20, 1S73, on the quantitative analysis of certain 

 alloys by means of the spectroscope. 



Attention is called in this Report to the teaching of 

 weights and measures in schools. There is no doubt that 

 a large number of obsolete and unnecessary weights and 

 measures are used in school text-books. The teaching of 

 the metric system of weights and measures is now aban- 

 doned in schools under the authority of the Education 

 Department. 



The use of the mirror and electric lamp has been so 

 eloquently demonstrated by Professor Tyndall, that our 

 readers will be glad to see appended to the Report a paper 

 on the employment of a mirror and a ray of light for 

 indicating diflcrences in standard weights, or in measures 

 of length. This paper is a translation of a paper by 

 C. A. Steinheil, read in 1S67 at the Imperial Academy of 

 Sciences at Vienna, and is a valuable record of the work 

 of one who spent his life in scientific research. 



Also appended to this Report is a short table for the 

 reduction to 0° C. of readings of barometers with metric 

 graduations on their glass tubes, based on those coeffi- 

 cients of the expansion of mercury and glass adopted in 

 standard measurements, viz. : — 



Cubic expansion of mercury , O'oooi 7971 for i" C. 



Linear expansion of glass . . o'ooooo8S6 „ 



As an instance of the precision with which measure- 

 ments are now made, we may refer to p. 40 of this Report, 

 from which it appears that the value of a micrometer was 

 determined at two different periods to be 0000031 Si and 

 o'oooo3i83 inch respectively ; showing a difference of 

 only O'ooooooo2 inch. Such precision may appear to be 

 scarcely necessary except in particular researches. As, 

 however, any error in the production of a direct copy of 



