;o6 



NATURE 



[January 26, 1905 



and Mr. J. Kent Smith. These steels appear to be most 

 valuable from their power of resisting rapid alternations 

 of stress and sudden shock, especially after they have been 

 subjected to special thermal treatment. The temperature 

 of their recalescence is at about 715° C, and the effect 

 of quenching in oil from 900° C. and subsequently re- 

 heating at 600° C. is to increase enormously the resist- 

 ance of the alloy to shock, as measured by an impact test, 

 and to alternations of stress, without affecting the tensile 

 strength. A spring of chrome-vanadium steel which was 

 prepared was found to have double the strength of an 

 ordinary steel spring of the same dimensions, the extension 

 being directly proportional to the load throughout a very 

 much wider range. Like the nickel steels, those which 

 contain vanadium and chromium are very efficient in with- 

 standing bending tests. 



Messrs. Dawb.irn and Ward, Ltd., have added a 

 booklet, "How to Read 'a Workshop Drawing," by Mr. 

 W. Longland, to their " Home-Worker's " series of 

 practical handbooks. 



A third edition of Mr. M. M. Pattison Muir's trans- 

 lation of Prof. Lassar-Cohn's " Chemistry in Daily Life " 

 has been published by Messrs. H. Grevel and Co. The 

 book has been revised and enlarged. 



A teachers' edition of part ii. of " Elementary Algebra," 

 by Messrs. W. M. Baker and .\.. A. Bourne, has been 

 published by Messrs. George Bell and Sons. Teachers 

 are likely to find the plan of printing the answers on the 

 page opposite to the examples a convenience in class 

 work. 



The Engineering Standards Committee has just issued 

 the " British Standard Specification for Portland Cement." 

 The specification deals with the quality and preparation 

 of the cement, gives particulars as to sampling and 

 preparation for testing and analysis, and goes on to 

 enumerate what should be its fineness, specific gravity, 

 chemical composition, &c. The specification also considers 

 at length the various tests which a satisfactory cement 

 should pass. Copies of the publication may be obtained 

 from Messrs. Crosby Lockwood and Son, price 2s. 6d.- 

 net. 



The 1905 issue of " Hazell's Annual " has now been 

 published. Twelve pages are devoted to scientific progress 

 during 1904, and about five to scientific societies and 

 institutions. Education in the United Kingdom in all 

 its branches is given some fourteen pages. 



OVR ASTRONOMICAL COLUMN. 



The Reported Sixth Satellite of Jupiter. — A telegram 

 from the Kiel Centralstelle gives the position of a minor 

 planet, P.V., photographed by Prof. Wolf on January 

 23.135 at the Konigstuhl Observatory, at yh. SSm. 

 (Konigstuhl M.T.), as 



R.A. = ih. 31m. 59s., dec. = -)-8° 3b' 13". 



The daily movement of this object is +23' in R..^. 

 and —9' in declination, and it is suggested that the body 

 may possibly be identical with the object announced by 

 Prof. Perrine as a sixth satellite to Jupiter. 



Periodical Comets due to Return in 1905. — In the 

 January Observatory Mr. W. T. Lynn directs attention to 

 the periodical comets which are due to return to peri- 

 helion this year. There are only two, of which the first, 

 Encke's, has already been seen, and passed through peri- 

 helion on January 4. The second is that discovered by 

 Prof. Max Wolf on September 17, 1884 (comet iii,, 1884), 



NO. liiS9, VOL. 71] 



which has a period, variously estimated, of about 6-76 

 years. This object returned as comet ii., 1891, and 

 comet iv., i8g8, its perihelion being passed during the 

 latter return on July 4, although its nearest approach 

 to the earth did not take place until the end of November. 

 Accordingly it should again pass through perihelion early 

 in April next. 



Changes on the Surface of Jupiter. — An interesting 

 popular e.xposition of the knowledge acquired during the 

 past twenty-five years concerning the conditions of, and 

 the changes on, the visible surface of Jupiter is given by 

 Prof. G. W. Hough in No. i, vol. xiii., of Popular 

 Astronomy. 



Prof. Hough's own observations of Jupiter have extended 

 over twenty-five years, and the present article summarises 

 them and the conclusions to which they have led him. 

 He particularly refers to the determined values for the 

 rotation periods at different latitudes, and sees no evidence 

 for the existence of any law connecting the two, giving 

 diagrams which illustrate the point. Two other diagrams 

 show the variations in the latitude and the rotation period 

 of the great red spot from 1879 to 1903, whilst yet 

 another illustrates the changes in the position and width 

 of the equatorial belt during the period 1895-1904. From 

 the latter diagram it is seen, very clearly, that the changes 

 in the northern part of the belt are much more sudden 

 and of a greater magnitude than those which take place 

 in the southern portion. 



Stars Having Peculiar Spectra. — During the examin- 

 ation of the Henry Draper memorial plates, Mrs. Fleming 

 has discovered some additional stars which are either 

 variable or have peculiar spectra. Thirty-one of these are 

 announced and briefly described in No. 92 of the Harvard 

 College Observatory Circulars. Of those having peculiar 

 spectra a few are worthy of special notice. For instance, 

 A. Cephei (mag. 5-6) was found to have a spectrum identical 

 with that of C Puppis, which hitherto has been regarded 

 as unique. The stars D.M. — 11° 1460 (Monoceros) and 

 -1-64° 1527 (Cepheus), amongst others, show a bright 

 H/8 line. In the former the ether hydrogen and the helium 

 lines are double, whilst in the latter they are single but 

 broad. The spectrum of D.M.-|-39° 4368 (R.A.= 

 2oh. 5i-6m., dec. = -|-39° 55', mag. = 72), as photographed 

 on September 15, 1904, was continuous, showing no trace 

 of lines, although the lines in the spectra of neighbouring 

 stars were sharply defined ; on other plates the hydrogen 

 lines show faintly, although the spectrum was not so well 

 defined. 

 ■V Real Paths, Heights, and Velocities of Leonids. — 

 From the observational data submitted to him by various 

 observers, Mr. Denning has computed the real paths, 

 heights above the earth's surface, and velocities of several 

 Leonids seen during the last shower. From three observ- 

 ations of the brightest meteor seen at Greenwich, at 

 i6h. 24m. 42s., November 16, 1904, he finds that the height 

 of this object was from 88 to 44 miles along a path 

 e.xtending not more than 60 miles from near Petersfield 

 to Hungerford. The velocity was about 46 miles per 

 second, and the radiant point was I5i°-f22°. 



A second meteor recorded by two observers w'as seen at 

 Greenwich, at November i4d. loh. 26m., and at Enniscorthy 

 (Ireland), 280 miles away. This had a long horizontal 

 flight from over the neighbourhood of Sheffield to near Car- 

 marthen, and was 83 to 78 miles high, the velocity being 

 about 40 miles per second. Another meteor travelled at a 

 height of 79 to 58 miles from over Faringdon to Stroud, 

 its visible path being 35 miles long and its velocity 39 

 miles per second {Observatory, January). 



New Method for Measuring Radial-velocitv Spectro- 

 grams. — At a meeting of the International Congress of 

 .'\rts and Sciences held at St. Louis in September, 1904, 

 Prof. J. Hartmann, of Potsdam, gave a brief outline of 

 a new method whereby he proposes to reduce considerably 

 the labour involved in measuring the displacements of 

 lines in stellar spectra for the purpose of determining the 

 radial velocities of the stars. Hitherto it has been 

 customary to measure the displacement of each line 

 separately, and subsequently to reduce the individual 

 measures: but in Prof. Hartmann's new method the dis- 



