134 



NATURE 



[April 17, 19 19 



lines of double width and with single-width spaces, 

 that portion exposed behind each colour may be alter- 

 nately isolated as the key-plate is shifted. This ad- 

 justment is done mechanically, identification marks 

 indicating which colour record is exposed, and as 

 contact prints cannot be obtained, an enlarging lan- 

 tern is used. The prints may be obtained " in any 

 one of a dozen different ways," but Mr. Williams 

 prefers the bromoil process, inking up with the three 

 necessary colours and superposing the prints by 

 transferring the ink images to drawing-paper. The 

 lines are not obtrusive in the resulting pictures, and, 

 if desired, they can be obliterated by putting the 

 image slightly out of focus when making the expo- 

 sures for the prints. The method of making the 

 screens is also described in the Photographic Journal 

 for March. 



In an address to the Franklin Institute, Phila- 

 delphia, which is reproduced in the Journal of the insti- 

 tute for January. Mr. H. Leffmann shows that the 

 pioneer experiments in aviation carried out by the late 

 Prof. S. P. Langley were complete enough to form the 

 basis for modern practice. In May, 1896, Prof. 

 Langley launched from a small island in the Potomac 

 an unmanned aeroplane driven by a steam-engine 

 which ascended to an altitude of 60 ft. or 70 ft., and 

 travelled at about twenty miles per hour for eighty 

 or ninety seconds before descending. With the help 

 of a grant from the Government and the mechanical 

 assistance of Mr. C. M. Manly, he constructed an 

 internal-combustion engine of 18 b.h.p. weighing 

 only 108 lb., and in 1903 Mr. Manly made an experi- 

 mental flight on a machine driven by this engine. 

 Through some accident not clearly understood, the 

 flight came to a premature conclusion, and the pilot 

 narrowly escaped drowning. Prof. Langley died in 

 1907 without making any further experiments, but in 

 iqi4 the^machine of 1903 was flown successfully by 

 Mr. G. H. Curtiss. When the engine was replaced 

 by one of 80 h.p. a number of flights were made 

 which demonstrated that the principles of the Langlov 

 machine were sound and practical. 



The Cambridge University Press is publishing for 

 Dr. A. E. Shipley, Master of Christ's College, and 

 Vice-Chancellor of the University of Cambridge, an 

 account of the author's experiences during his 

 recent visit to the United States of America. It will 

 be entitled "The Voyage of a Vice-Chancellor." 

 " The Furniture Beetle " is in preparation for appear- 

 ance in the series of Economic Pamphlets of the 

 British Museum (Natural Histor}'), and "The Danger 

 of Disease from Fleas and Bugs " for appearance in 

 the Museum's series of Economic Leaflets. Mr. W. 

 Heinemann is about to publish " Psychology and 

 Parenthood," by H. A. Bruce, who aims at presenting 

 to parents particulars of the discoveries in child-nature 

 obtained by psychologists and others. Messrs. Long- 

 mans and Co. announce a book which should be of 

 interest to educationists, viz. "The Manchester 

 Grammar School, 1515-1915 : A Regional Survey of 

 the Advancement of Learning since the Reformation." 

 The author is Dr. A. A. Mumford. 



OUR ASTRONOMICAL COLUMN. 

 Observed Changes on Jupiter. — Some remarkable 

 alterations in the surface-markings of this planet 

 have been observed recently. The bay or hollow in 

 the south equatorial belt, which has; been almost un- 

 interruptedly visible since Schwabe figured it in Sep- 

 tember, 18-^1, appears to have disappeared. Mr. F. 

 Sargent, of Bristol, using telescopes of 10^ in. aper- 

 ture (reflector) and 5 in. (Cook refractor), has been 

 unable to see any distinct traces of the feature named 

 during his verv recent observations. It was an im- 



portant marking as serving to show the position of 

 the great red spot, which has been very faint during 

 a long series of years. In 1901 a large dark mass 

 made its appearance in the south tropical zone of 

 Jupiter, and in about the same latitude as the red 

 spot. This moved with greater speed than the latter, 

 its rate of rotation being about 12 seconds less, and 

 the marking had so greatly extended in longitude that 

 in January and February of the present year it ranged 

 over about 180°, or half the planet's circumference. 

 This object seems also, practically to have disappeared. 

 Mr. Sargent saw the following end of it central on 

 March 7 at loh. 13m. in longitude 60-3°, but it was 

 extremely faint, and regarded as near the vanishing 

 point. Since that date observations have failed to 

 reveal the object, though the disc has beeri carefully 

 scanned at those times when it must have been pre- 

 sented to view had it continued visible. 



Drawings of Mars. — Popular Astronomy for 

 February . contains an interesting series of compara- 

 tive drawings made by five observers at the last 

 opposition, according to a prearranged scheme 

 organised by Prof. W. H. Pickering. On the whole, 

 the accord of the different draughtsmen is satisfac- 

 tory; thus of 131 canals appearing on the sketches, 

 eighty-three are confirmed by at least one other 

 observer. The Rev. T. E. R. Phillips noted that he 

 could see nothing with the Greenwich 28-in. that was 

 not visible in his own 8-in. Several observers men- 

 tion the beautiful blue tint of Syrtis Major ; the other 

 maria tended to grey or brown. 



The Gegenschein or Counterglow. — ^This pheno- 

 menon has a great fascination for Prof. Barnard, 

 who in 1899 published his observations extending 

 over sixteen years. Prof. Barnard made another 

 series last autumn (which he states to be the best 

 season to observe it), and gives the results in Popular 

 Astronomy for February. As in the previous set, the 

 longitude comes out exactly 180° from the sun, the 

 latitude 0-3° N. The diurnal parallax appeared to be 

 insensible. He favours the explanation that it is an 

 atmospheric phenomenon, the earth's atmosphere 

 acting as a spherical lens and concentrating the sun's 

 light. He mentions two other explanations as 

 possible : that of Evershed, that the earth has a tail 

 like a comet; and that of Moulton, that there is an 

 aggregation of meteoric bodies at the point opposite 

 the sun describing periodic orbits under the combined 

 action of sun and earth. 



Tycho Brake's Original Observations. — An 

 article by Dr. J. L. E. Dreyer in Scientia for March 

 states that the manuscript books in which Tycho's 

 observations were entered night by night were sold 

 to the King of Denmark, and are now in the Royal 

 Library at Copenhagen. A contemporary fair copy 

 of most of them is now in the Imperial Library at 

 Vienna, and from this copy an edition was prepared 

 bv a Jesuit named Curtius in 1666. This is known 

 to be very incomplete and incorrect, and a new edition 

 is being prepared by Dr. Dreyer from the original 

 observing books and from the copy at Vienna, which 

 will form vols, x.-xiii. of the collected works of Tycho 

 Brahe, now being printed at Copenhagen. 



NO. 2581, VOL. 103] 



THE DEVELOPMENT OF AIRSHIP 

 CONSTRUCTION. 



A MONG the important papers read last week at the 

 ■^"^ Institution of Naval Architects was one on airship 

 construction by Mr. C. I. R. Campbell, who has been 

 responsible at the Admiralty for the design of our 

 airships. In British practice it is assumed for design 

 purposes that the gas has a lift of 68 lb. per 1000 



