August 19. 1909J 



NA TURE 



229 



instrument used consists of an oxy-hydrogen, oxy-coal-gas, 

 or oxy-acetylene mixed blowpipe, tlirougli which an addi- 

 tional stream of oxygen can be supplied at will by the 

 operator. The object is to heat to incandescence the part 

 on which the jet of oxygen is afterwards to play, and to 

 keep it at that high temperature all the time the oxygen 

 jet is operating. This method has been found to overcome 

 entirely the older difficulties with regard to unsteady 

 manipulation of the oxygen jet, as well as the trouble due 

 to the presence of iron oxide. Plates and slabs of 

 steel up to 12 inches in thickness can be cut by this 

 method. The cut is very clean, and, in one example illus- 

 trated, where a slab of steel 8 inches thick was cut into 

 pieces f inch in width, the width oi the cut was only 

 about 5 inch, showing the intensely local nature of the 

 operation. .Another illustration shows an armour plate 

 being cut circular by means of a special appliance carrying 

 a blowpipe, the thickness of the plate in this example being 

 9 inches. The cut surfaces are left comparatively smooth, 

 and the cut is square down from the face of the plate, 

 although it is possible also to make bevel cuts. All grades 

 of steel can be operated on. 



Mr. H. K. Lkvvis, of Gower Street, London, has sent 

 us a copy of a catalogue of the new books and new 

 editions added to his medical and scientific circulating 

 library during the second quarter of this year. The list 

 will be sent post free to any address on application. 



A SECOND edition of Prof. Marcel Moye's translation 

 of Prof. Lowell's " Mars and its Canals " has been pub- 

 lished at the office of the Mercure de France, Paris. The 

 original volume has already been reviewed in these 

 columns, and we are glad of this opportunity of con- 

 gratulating Prof. Moye on the demand for a second edition 

 of his translation of Prof. Lowell's interesting book. The 

 price of the translation is five francs. 



Sir William Ramsay's volume of " Essays, Biographical 

 and Chemical," which was reviewed in Nature of July 20, 

 has been translated into German by Prof. W. Ostwald, and 

 published by the Leipzig Akademische Verlagsgesellschaft, 

 under the title, " Vergangenes und Kunftiges aus der 

 Chemie. " The German volume includes, in addition to the 

 essays of the original work, an autobiographical sketch bv 

 Sir William Ramsay, occupying thirty-five pages. 



OUR ASTRONOMICAL COLUMN. 



Observations of .Mars. — Circular no from the Kiel 

 Centralstelle announces that, at 2 p.m. on August 12, 

 M. R. Jonckheere observed a brilliant spot detach itself 

 from the polar snows of Mars and cover the Novissima 

 Thyle, in longitude 320°. 



In No. 4340 of the Astroiwmischc Nachrichten M. Jarry 

 Desloges records some observations of Mars made at the 

 Mussegros Observatory (Lozere) during June and July. 



On June 20 and 23 a dark cutting was seen in the south 

 polar snows, in longitude about 190°, and appeared to 

 terminate in a rounded spot, which was of a darker shade. 

 The crevasse observed by Prof. Lowell in longitude 350° 

 was easily seen on July 4 with a 37 cm. refractor installed 

 on the Revard plateau, and appeared to traverse the whole 

 length of the visible part of the snow-cap. On the same 

 day, at 4I1. 15m. a.m., a broad, bright spot was seen on 

 the dark edge of the snow in about longitude 30°. 



Re-discovery of Perrine's Comet. — A telegram from 

 the Kiel Centralstelle announces that comet Perrine was 

 discovered by Herr Kopff at loh. S4m. (M.T. Konigstuhl) 

 on August 12. The position of the comet at that hour 

 was R.A. = oh. 171m., dec. = 35° 32' N., and the magni- 

 tude was 150. 



Of the three ephemerides given by Herr Ristenpart, the 

 NO. 2077, VOL. 81] 



first (T = October 275) gives the nearest position to the 

 above for August 12, the ephemeris place being 



R.A. = oh. 4o-2m., dec. 36° 45-9' (igio-o). 

 The Number of the St.4RS. — In the August number of 

 the Observatory (No. 412, p. 323) Mr. Gavin Burns directs 

 attention to the discrepancy between the Groningen and 

 the Harvard estimates of the total number of stars, and 

 suggests that Prof. Kapteyn's estimate is probably 

 excessive. Tabulating the figures given by each of the 

 two observatories, he shows that from the tenth magni- 

 tude downwards the Groningen numbers are greatly in 

 excess of those given by Prof. Pickering ; for example, 

 the respective totals, including all stars down to the 

 10-5 magnitude, are 697,551 and 604,000, but if the 13-5 

 m,a'gnitude be included they are 14,582,551 and 6,761,000. 

 Then there is a note in the Harvard publication which 

 suggests that if stars to the fifteenth magnitude were in- 

 cluded the total would be raised to about 18 million, 

 whereas Prof. Kapteyn's estimate for magnitude 145 is 

 38 million, and for magnitude 15-5 98 million. A published 

 investigation of the Greenwich astrographic plates shows 

 agreement with Harvard for the fainter magnitudes, and 

 strengthens the suggestion that the Groningen estimates 

 are too high. 



The Faint Companions of Procyon and Sirius. — • 

 During last winter Prof. Barnard employed the Yerkes 

 40-inch refractor on many occasions in an endeavour to 

 detect and measure Schaeberle's faint companion to 

 Procyon, but only on a few occasions was he successful. 

 The results, which are published in No. 4345 of the Astro- 

 noinische Nachrichten (p. 13, August 7), show that during 

 the last five or six years the angular motion of the com- 

 panion has been about 5-2° per annum, but the distance 

 has changed but little. The weighted means, for 1909- 162, 

 were 22-51" and 5-26" respectively. Prof. Barnard states 

 that the least atmospheric diffusion of the light of the 

 large star hides the close companion, and then explains a 

 device which he uses to obviate the adverse effect of the 

 stray light. This is to place a hexagonal diaphragm over 

 the 40-inch object-glass so that the angles of the hexagon 

 lie on the periphery of the glass. This collects the stray 

 light into six thin bright rays, and the small star can be 

 more easily seen in the dark space between a pair of the 

 rays. 



A similar device was employed in observing the faint 

 companion to Sirius, and the measures made during the 

 period 1903-9 are given in the same journal. These show 

 that the angle is decreasing, from 115-38°, for 1903-808, 

 to 92-53°, for 1909-135, whilst the distance is increasing, 

 the values for the corresponding epochs being 632" and 

 8-75" respectively. 



Prof. Lowell's New 40-iNCH Reflector. — .A brief 

 description of the new 40-inch reflector which Messrs. 

 .Alvan Clark and Sons are just completing for Prof. 

 Lowell appears in No. 412 of the Observatory. The focal 

 length is 18 feet 4 inches, and the mirror, cast at St. 

 Gobain, is 7 inches thick and weighs more than 900 lb. 

 The cell is an iron ring with zinc blocks so arranged that 

 the combined expansion is the same as that of the glass, 

 thus obviating distortion. For planetary photography the 

 reflector can be used as a Cassegrain of 154 feet, or 75 feet, 

 focal length, whilst for stars and nebulas it will be used 

 as a Newtonian with the plate at the principal focus. In 

 order to protect the instrument from the wind, and partially 

 from large temperature changes, it will be mounted in 

 a pit sunk 6 feet into the ground, over which is erected 

 a hemispherical dome of wood and canvas. The requisite 

 diurnal motion is to be imparted to the instrument by two 

 electric motors, one for driving, the other for slow motion. 



Water 'Vapour in Sun-spots. — In the July number of 

 the Aslrophysical Journal (vol. xxx.. No. i, p. 44) Mr. 

 W. M. Mitchell discusses the various researches which have 

 led to the suggestion that water vapour exists in sun- 

 spots. He points out that the spectroscopic evidence is not 

 unanimous, either for or against, and is certainly not 

 conclusive. 



The affected spot lines may be due to other substances 

 not yet identified, and giving lines of nearly similar wave- 

 length. Then the apparent intensification may be a sub. 



