♦ KNOAVLEDGE 



[Sept. 11, 1885. 



looking as one of the old astronomers said, like a candle 

 ill a horn lantern, and so it appears in tlie photograph. 

 Now it appears as an intensely bright point, entirely- 

 different in character and very much more brilliant than 

 before. 



" About two minutes of arc from this new bright point 

 there is a faint star many magnitudes less bright ; this 

 faint star shows on the photograph as bright, though not 

 so large, as the old central condensation. I have no 

 doubt we have hero a case of real change taking place, 

 and that astronomers will watch further developments 

 with intense interest. A. A. Common, F.R.S." 



" Ealing,' Sept. 4. 



" Sir, — The sudden appearance of a new star in the 

 heavens is a rare event, which is so full of interest to 

 many of your readers that it deserves to be carefully 

 chronicled. 



" On Aug. 31 Dr. Hartwig, of Dorpat, announced the 

 discovery of a variation in the Andromeda nebula pre- 

 senting the form of a starlike nucleus. Thanks to Lord 

 Crawfnnl's |iroin]it dissemination of such astronomical 

 news l.y im-aiis (if the Dun Echt circulars, astronomers 

 werr unuiMJly iuformed of the discovery by Sept. 2. 



"La.sl ivruiug (Sept. 3), on examining the Andromeda 

 nebula, the object was found to be conspicuously visible 

 as a star of the eighth or ninth magnitude shining 

 through the densest region of the nebula. It does not at 

 all present the aspect of a nucleus to the nebula, and at 

 present I have not been able to' detect any ch.ange in the 

 nebula itself. It seems evident, therefore, that the 

 object is one of those' enigmatical variable stars, such as 

 were observed to suddenly blaze forth by Tycho Brahe in 

 Cassiopeia, by Kepler in Serpentarius, and more recently 

 in 1866 by the late Mr. Birmingham in Corona. 



" Three sets of photometric comparisons with another 

 star were secured. The small st.ar adopted for a standard 

 was one of the eighth magnitude in the Perseus cluster, 

 and was selected because (1) it was about the same alti- 

 tude as the new star, (2) observations for several years 

 had shown that its light was not appreciably variable, 

 and (3) because estimations of its magnitude are known, 

 and moreover it is to be identified in the exquisite photo- 

 graph of this cluster by the MM. Henry, at the Paris 

 Observatory. 



" Assuming this star as of 8-1 magnitude (it is probably 

 rather higher), then the three sets of photometric 

 measures, made on the principle of limiting apertures, 

 give for the date 1885, September 3, 9 p.m. to 11 p.m — 

 'Nova Stella,' 8-8 magnitude, three observations; 87 

 magnitude, eight observations ; 8'7 magnitude, four obser- 

 vations ; mean 8-72 magnitude. 



" If your readers will look towards the east between 

 nine and ten o'clock in the evening, and rather high up, 

 they will see a small misty spot of light — that is the 

 Andromeda nebula — and on taking an opera glass they 

 will not fail to detect in the middle of this misty spot a 

 small star, which is the new one just started into visi- 

 bility. To the specti'oscope we must look to learn 

 something of the nature of this remarkable oatburst. 



" Edwaed B. Knobel. 



" Becking, near Braintree, Essex, Sept. 4." 



The chairman and directors of the Great Western Railvvaj- pro- 

 ceeded through the Severn tunnel in a special train on Saturday 

 fast, accompanied by a number of friends. The tunnel is to be 

 lormally opened by the Prince of Wales some months hence. 



FIRST STAR LESSONS. 

 Br RicHAED A. Peoctok. 



1'^HE constellations included in 

 of this series are numbered 

 (the names being omitted on tl 

 fai as possible from all that 

 grouping less distinct) : — 



1. Ursa Minor, the Little Bear 



{a, the Pole Star). 



2. Draco, the Dragon (a, 



Thuban) 



3. Cepheus, King Cepheus. 



4. Cansiopeia, the Lady in the 



Chair. 



5. Perseus, the Champion (ft, 



Algol, famous variable). 



6. Auriga, the Charioteer (a, 



Capella) 



7. Ursa Major, the Greater 



Bear (a, ft, the Pointers). 



8. Canes Venatici, the Hunting 



Dogs (a, Cor Caroli). 



9. Coma Berenices, Queen 



Berenice's Eair. 



10. Bootes, the Herdsman (a, 



Arcturus). 



11. Corona Borealis, the Nor- 



them Crown. 



12. Serpens, the Serpent. 



13. Hercules, the Kneeler. 



14. Lyra, the Lyre (a, Tega). 



15. Cygnus, the Swan (a, 



Arided; ft, Albires). 



16. Pegasus, the Winged Horse. 



17. Andromeda, the Chained 



Lady. 



18. Triangula, the Triangles. 



19. Aries, the Bam. 



20. Taurus, the Bull (o, Aide- 



haran; ij, Alcyone, chief 

 Pleiad). 



21. Gemini, the Twins (a, 



Castor ; ft, Pollux). 



the twenty-four maps 

 throughout as follows 

 majjs, to clear these as 

 light render the star- 

 Cancer, the Crab (the 



cluster is the Beehive). 

 Leo, the Lion (o, Regulus). 

 Virgo, the Virgin (o, Spica). 





, the Scales 



Ophiuchus, the 

 Holder. 



Aquila,the Eagle (a,Altair). 



Delphinus, the Dolphin. 



Aquariius,the Water Carrier. 



P,sces. the Fishes. 



Cetus, the Sea Monster (o, 

 Mira, remarkable va- 

 riable). 



Eridanus, the Rtoer. 



Orion, the Giant Hunter 

 (a, Betelgeux; ft, Rigel). 



Canis Minor, the Lesser Dog 

 (a, Procyon). 



Hydra, the Sea Serpent (a, 

 Alphard). 



Crater, the Cup (a, Alkes). 



Corvus, the Crow. 



Scorpio, the Scorpion (a, 



Sagittarius, the Archer. 

 Capricornus, the Sea Qoat. 

 Piscis Australis, the Sou- 



them Fish (a, Fomal- 



haut). 

 Lepus, the Hare. 

 Columla, the Doie. 

 Canis Major, the Greater 



Dog {a,Sirius). 

 Argo, the Ship. 



FINDING THE WAY AT SEA. 



By Richard A. Proctor. 



{Continued from page 194.) 



IT will be clear to the reader, by this time, that the 

 great point in determining the longitude, is to have 

 the true time of Greenwich or some other reference 

 station, in order that by comparing this time with ship 

 time, the longitude east or west of the reference station 

 may be ascertained. Ship time can always be deter- 

 mined by a morning or afternoon observation of the sun, 

 or by observing a known star when towards the east or 

 west, at which time the ditirnal motion raises or de- 

 presses it most rapidly. The latitude being known, the 

 time of day (any given day) at which the sun or a star 

 should have any particular altitude is known also, and, 

 therefore, conversely, when the altitude of the sun or a 

 star has been noted, the seaman has learned the time of 

 day. But to find Greenwich time is another matter; 

 and without Greenwich time, ship time teaches nothing 

 as to the longitude. How is the voyager at sea or in 

 desert places to know the exact time at Greenwich or 

 some other fixed station? We have seen that chrono- 

 meters are used for this purpose ; and chronometers are 

 now made so marvellously perfect in construction that 

 they can be trusted to show true time within a few 

 seconds, under ordinary conditions. But it must not be 

 overlooked that in long voyages a chronometer, however 



