October 24, 1901] 



NATURE 



639 



OUR ASTRONOMICAL COLUMN. 

 The Spectroscoi'IC Binary Capei,la. — The Lick Oisema- 

 tory Bullelin No. 6 contains the final values adopted for the 

 orbit of the spectroscopic binary system of Capella. The re- 

 ductions are from thirty-one observations of the radial velocity 

 of the solar-type component, made with the Mills spectrograph 

 between 1896 September i and 1900 September 27. On most 

 of the plates the spectra of the two components are distinguish- 

 able, that of the principal star being of the solar type, whereas 

 that of the secondary component is intermediate between 

 the solar and Sirian types. The ranges in velocity are as 

 follow : — 



Principal star +4'2 to -H55'7 kilometres per second.. 



Secondary,, -3 ,, -f63 ,, ,, 



Therefore the ratio of the two masses will be as i '26 : i. 



The solar-type component is estimated to be about half a 

 magnitude brighter photographically than the blue component, 

 while in the visual region of the spectrum the solar component 

 is probably a whole magnitude the brighter of the two. 



In consequence of observations with the 36-inch refractor 

 under good conditions failing to show the duplicity of star, it 

 i's probable that the distance between the components is not 

 greater than o"'o6 . 



The following are the final adopted elements, with their several 

 probable errors : — 



" = ii7°-3 ± i8°-3. 



ju — o'o6o403 + O"ooooi4 radians. 



= 3°'46oS2 + o°'oooSi. 

 T = - ■7'4 ± 5'3 days, the actual date being 



1S99 September 1-5. 

 e =0 0164 + o'0O55. 



K = 2576 + 0'12. 



U = 1 04 "022 days + 0'024 days. 



<jsin/= 36,847,900 kilometres. 

 V = + 30'I7 + 0'I04 kilometres per second. 



New Southern Ai.gol-Variahi.e. — Mr. A. W. Roberts 

 announces that observations made at Lovedale confirm the 

 variability of the star, 



R.A. = loh. l6m. 44s. "| o 



Decl. = -4i°43'-8 /'^/S- 



The observations suggest the following elements : — 



Period = id. 2oh. 30m. 2s. 



Epoch of Min.= 1900, Jan. id. I5h. lom. (G.M.T.) 



Limits = loo-io'9 magnitude. 



The actual light changes are completed in 3h. 20m., and there 

 appears to he no stationary period at minimum. The ascending 

 and descending phases are equal, each occupying ih. 40m. 

 {Astronomical Journal^ vol. xxii. No. 508.) 



Spectrum of Nova Pbrsei. — In the Astro>iomische Nach- 

 richteii, Bd. 156, No. 3741, Father Sidgreaves summarises as 

 follows the results of his examination of recent photographs of 

 the spectrum of the Nova Persei : — ■ 



All hydrogen lines are now relatively weak, excepting the 

 doubtful line He. 



A5007 much stronger than H6 or II7. Great width. 



4958 prominent broad band. 



4718 grown from a weak to strong band. 



4713 strong line on edge of 4718. 



468S rather weak broad band. 



4640 gradually weakened like hydrogen. 



4364 very prominent band, stronger than H7, crossed by 

 three bright lines. 



3969 ?H€. As strong as all other hydrogen lines together. 



3869 stronger than 3969. 

 All these, with the exception of 4718, which shades off on red 

 side, are broad with sharp edges. The structure of bands 3969 

 and 3869 very remarkable, being crossed by four strong lines of 

 the same relative intensities and at the same intervals. This is 

 also shown in the line 4364. 



MicROMETKic Observations of Neptune and its 

 Satellite. — In the Astronomical Journal^ vol. xxii. No. 

 508, Prof. E. E. Barnard gives a series of micrometer measures 

 of the satellite of Xeptune extending over the period 18S9 

 August 12 — igoi February 5. made with the 40-inch refractor 

 of the Yerkes Observatory. Many observations had been re- 



NO. T669, VOL. 64] 



corded previously, but it has been pointed out by Prof. Hall that 

 only continuous measures of this object are of value. For the 

 majority of the observations a power of 700 diameters was 

 employed. 



On three occasions it was possible to obtain good measures of 

 the diameter of the planet, the reduced value being 

 d = 2 "'436 (at mean distance = 30'o55i). 

 A note is made of the fact that the planet, -.vhen seen under the 

 best conditions, always appeared round and free from markings. 



Appearance of the Photographic Ima(;e of Nova' 

 Persei. — MM. Flammarion and .Antoniadi contribute a further 

 article respecting the photographic image of Nova Persei to the 

 October issue ol the Bnlktin de la Socit'tJ Astronomique, which 

 is specially interesting in that it is illustrated by drawings and 

 reproductions from the photographs obtained, showing exactly 

 the appearances presented. These have already been described; 

 the suggested explanation by Dr. Max Wolf ascribing them to 

 the objective not being corrected for some special radiation 

 emitted by the Nova does not appear to have been definitely 

 settled yet, but the great intensity of the ultra-violet lines in its 

 spectrum, together with the fact of the existence of the newly 

 observed line about A 342, would seem to support this sup- 

 position. 



RECENT PROGRESS IN WATERWAYS AND 



MARITIME WORKS. 

 'T'HE fourteen pipers presented to the section of Waterways 

 and Mari'.iine Works at the International Engineering 

 Congress at Glasgow were for the most part descriptive of im- 

 portant recent works carried out in various parts of the world, 

 as, for instance, the Dortmund and Ems Cmal, the Assu^n 

 Reservoir Dam across the Nile, the improvement of the Lower 

 Mississippi, the Chicago Drainage Canal, the breakwaters for 

 sheltering the entrance to the River Nervion, the Zeebrugge 

 Harbour Works, and recent improvements in the lighting and 

 buoying of the Scottish and French coasts. Some papers, 

 moreover, dealt with the gradual extension and recent progress 

 of works commenced many years ago, as, for example, the 

 improvement of the River Clyde and its estuary and the works 

 of Glasgow Harbour, recent improvements in the navigable 

 condition of the Sulina branch and outlet of the Danube, and 

 the lighting of the Chinese coast. 



Some of these works furnish, for the most part, a record of 

 the steady development and extension of methods of execution, 

 constituting in the end a very notable advance, of which, how- 

 ever, the stages have been numerous and gradual ; whilst other 

 works present distinctly novel features, exhibiting a very definite 

 progress in engineering science, and therefore of somewhat 

 special interest, as will be briefly indicated. 



The lift at Henrichenburg, on the Djrtmund and Ems Canal, 

 for raising barges of 95c tons from one reach of the canal to 

 another, 46 feet higher, in a single operation, illustrates the 

 novel principle of supporting the trough, carrying the barge, 

 on several floats immersed in wells ; and the whole structure is 

 so perfectly balanced that the introduction of a small quantity 

 of water into the trough at the top causes it to descend, and 

 the abstraction of some water from the trough when at the 

 bottom makes it ascend, the actual transit being effected in two 

 and a half minutes, though the whole operation of transferring 

 a barge from one reach to the other occupies about twelve and a 

 half minutes on the average. This system of simple flotation, 

 in place of the older system of hydraulic lifts, consisting of two 

 counterbalancing troughs, each supported centrally on a hydraulic 

 piston which even for raising barges of from 300 to 400 tons 

 has had to be given a diameter of 6i feet, has enabled 

 these canal lifts, with their important advantages over locks of 

 saving largely both time and water, to be adopted for vessels of 

 more than double the tonnage of those raised bv the older canal 

 lifts. 



The large excavations required for the Chicago Drain.ige Canal 

 led to the adoption of excavators and dredgers of unusual size, 

 the bucket of some dipper dredgers having been given a capacity 

 of six cubic yards ; whilst the removal of large masses of earth- 

 work to the sides of the canal trench gave rise to the intro- 

 duction of novel types of plant. These consisted of cableways 

 suspended from high travelling towers on each side ol the canal, 

 along which skips conveyed the earthwork from the excavations to 



