424 



NA TURE 



[March 5, 1903 



formations in the Indian Ocean, marine crustaceans and 

 the Lithothamnia. The first part of the second volume will 

 be published next June. 



An index, prepared by .Mr. Clement Reid, F.R.S., for 

 Dp la Beche's " Report on the Geology of Cornwall, Devon 

 and West Somerset," has recently been published for the 

 Geological Survey, and can be obtained from any agent for 

 the sale of Ordnance Survey maps. The Report was 

 published in 1S39, unfortunately without an index. No less 

 than 1500 copies were issued, and the memoir is now out 

 of print. It has, however, become one of the classics of 

 geology, and being a permanent work of reference, an index 

 has been a great desideratum, which has now been supplied. 



Messrs. John J. Griffin and Sons, Ltd., have sent for 

 our inspection a simple mechanical device for obtaining 

 rapidly any required set of numbers having the same ratio 

 ami rig themselves as any other given set of numbers. The 

 instrument is known as the " ratiometer, " and was designed 

 by Mr. A. E. Munby. It is made of boxwood, and consists 

 of two graduated rules, which can be set at any angle, 

 which with one edge of a T-square form a right-angled 

 triangle. By. means of a tongue and groove the base of the 

 ti angle slides along the stock of the T-square. The ratio- 

 meter should prove of great assistance to examiners for the 

 reduction of marks. It would be useful in laboratories, 

 whi re it could be used for such operations as the conversion 

 ■ I 1 1 ntimetres to inches, or of scales of temperature, and in 

 the office and workshop for converting one linear scale into 

 another when no simple ratio exists between the two, or 

 for finding the value of various quantities of goods. 



The international committee on atomic weights, organised 

 in 1900, and composed of more than fifty representatives 

 from chemical and other societies, has by vote designated 

 a smaller body of three representatives to carry on the 

 future work of the committee. The three elected members, 

 Profs. Clarke, Thorpe and Seubert, have just issued their 

 annual report and recommendations. It is pointed out that 

 upon the question as to whether oxygen or hydrogen shall 

 be taken as basis of the atomic weight numbers, opinion at 

 the present time seems to be evenly divided. To force the 

 adoption of either appears to be impossible, and experience 

 must be the final arbiter. That standard which best serves 

 to coordinate chemical and physical knowledge will ultim- 

 ately be chosen, and the other will gradually fall into dis- 

 use. Tables are appended to the report in which both 

 standards of atomic weights are represented. In view of 

 recent work, the committee has thought it necessary to 

 make changes and recommendations in respect to the atomic 

 weights of antimony, germanium, hydrogen, lanthanum, 

 mercury, palladium, selenium, tin, uranium and zirconium. 

 Radium appears for the first time in the table with an atomic 



U'-ight = 225. 



Up to the present time very few instances of chemical 

 < hanges which exhibit periodicity have been observed. Very 

 recently it was found by Ostwald that the velocity of solution 

 of certain samples of chromium in acids does not change 

 in a continuous manner as would be theoretically antici- 

 pated, but that the rate of solution increases and decreases 

 periodically. An apparently similar change has been found 

 by Bredig and Weinmayr in the catalytic decomposition of 

 hydrogen peroxide by means of metallic mercury. An 

 account of the authors' experiments is given in the current 

 number of the Zeitschrijt fitr physikalische Ckemie. In 

 successive intervals of time the amounts of hydrogen per- 

 oxide are alternately larger and smaller, and the alter- 



NO. I/40, VOL. 67] 



nation appears to be simultaneous with a change in the 

 character of the mercury surface. Preliminary experiments 

 indicate that the alternations of the catalytic activity of 

 the mercury are intimately connected with alternations in 

 its electrical condition. In the inactive condition the mer- 

 cury is considerably more electro-positive than in the active 

 condition. 



OUR ASTRONOMICAL COLUMN. 

 Astronomical Occurrences in March :— 

 March 10. 4h. 59m. to 5h. 50m. Moon occults a Cancr' 

 (mag. 4-3). 



14. uh. 40m. Minimum of Algol (/3 Persei). 



15. Venus. Illuminated portion of disc =o"904, of 



Mars = 991. 

 15. Venus. Apparent diameter = n"'2, Mars = 13'' 8. 

 17. Sh. 29m. Minimum of Algol (/3 Persei). 

 iS. i6h. im. to I7h. 25m. Moon occults x Ophiucbi 



(mag. 5-0). 

 21. 7h. Sun enters Aries, Spring quarter commence*-". 

 25. Perihelion Passage of Giacobini's comet (D 1900). 

 28. 14I1. 5m. Annular eclipse of the sun, invisible at 



Greenwich. 

 2S. 20h. Mars in opposition to the sun. 

 30. 2oh. Venus in conjunction with the moon, Venus 



2 13' N. 



Comet 1903 a. — M. Paul Briick, of the Besancon Ohserv- 

 atory, publishes an ephemeris for this comet, irom which I he 

 following is an abstract, in No. 3S47 of the Astronomisrhe 



Nat /in, hicn. 



Paris \2>i. M.T. 



Date. 



6 app. 



log J 



log. a Brightness 



a. app. 

 h. m. s. , 



Mar. 6 o 13 52 + 17 27-9 



,, 8 o 18 26 + 18 3-9 9/6919 00141 iS'i 



,, 10 o 22 57 + iS 31-8 



,, 12 27 18 + 18 48-1 9'96o2 



,, 14 o 31 22 + 18 48-5 



,, i 6 ° 35 3 +1827-9 9'625i 9-9010 41-3 



From an observation by M. Chofardet on February 13, a 

 correction of Aa=-4s., A5=-o''2 to this ephemeris was 

 obtained, and the magnitude was recorded as about 9"0. 



The comet was observed at Lyons by MM. G. le Cadet 

 and J. Guillaume on various dates between January 21 and 

 29, and they record it as " a faint nebulosity without elonga- 

 tion and without tail." 



A new set of elements, published in the same journal by 

 M. G. I r avet, gives the time of perihelion passage as March 

 18-7092 M.T. Paris. 



Comet 1902 b (Perrine). — An ephemeris for this comet 

 is published in No. 3847 of the Astronomische Nachrichten, 

 by Herr Ebell, as a continuation of that which appeared 

 in No. 3841 of the same journal. It indicates that the comet 

 is rapidly becoming fainter, and an observation made at 

 Strasburg on February 17 showed that, on that date, the 

 magnitude was only about 11 '5. 



Herschel's Nebulous Regions of the Heavens. — Com- 

 menting on Dr. Isaac Roberts's recently published results, 

 which indicated that only four of the fifty-two nebulous 

 regions described by Herschel in 1S11 really contained nebu- 

 losities, Prof. E. E. Barnard remarks that this question is 

 likely to prove an important factor in future discussions as 

 to the physical condition of the universe, and then proceeds 

 to explain that the negative results obtained by Dr. Roberts 

 may be due to insufficient exposure, and that it is highly 

 improbable that Herschel should have been so palpably mis- 

 taken in forty-eight cases out of his fifty-two regions. 



In support of his argument Prof. Barnard proceeds to 

 describe several photographs, which he has obtained with 

 a 1'5-inch magic lantern lens of 4-9 inches equivalent focus, 

 which suggest that in one or two cases at least Dr. Roberts's 

 conclusions require further consideration. 



One striking instance is illustrated by a reproduction 

 showing a great curved nebulosity which embraces the 



