No%-EMBER 2, 1896.] 



KNOWLEDGE. 



251 



abruptly at two hours before midnight, foJlowing the first 

 significant twitch. Two double waves occurred during the 

 night, followed by a steady increase at sunrise, and a 

 series of small but rapid fluctuations which lasted all day. 

 A strong double wave of 17' occurred soon after sunset, 

 and the disturbance then gradually died away. In some 

 parts of England considerable auroral displays were 

 noticed during the nights of September 17th and 18th. 



It is with great regret that we learn, at the time of going 

 to press, of the sudden death of the distinguished Director 

 of the Paris Observatory, M. Francois Fti-lix Tisserand, in 

 his fifty-second year. M. Tisserand had only been in 

 command of the observatory four years, succeeding to that 

 post on the death of Admiral Moucbez. 



Utttcrs. 



[The Editors do not hold themselves responsible for the opinions or 

 statements of correspondents.] 



PEIS5IATIC LUXAE. RAINBOWS. 

 To the Editors of Knowledge. 



SiBs, — On the 21st September, at 7.2G p.m., I noticed a 

 very fine lunar rainbow. It appeared to be similar to a 

 solar rainbow, except that it was fainter. The prismatic 

 colours were distinctly visible. It gradually faded away, 

 and by 7.41 p m. it had completely disappeared. 



I again witnessed a similar phenomenon on the 23rd 

 September, at 7.30 p.m. The bow was, however, less 

 bright than on the preceding occasion, but the red and 

 blue were faintly visible. It had disappeared by 7.33 p.m. 



J. M. Wadmore. 



To the Editors of Knowledge. 



Snts, — On September 20th, at twenty minutes to ten, 

 I had the opportunity, in company with another, of 

 witnessing a very beautiful phenomenon. 



A dark and massive rain-cloud, which was travelling 

 rapidly towards the east, was seen to have a peculiarly 

 vivid prismatic corona on its western edge. The position 

 of this cloud seemed very much in advance of another thin 

 cloud of pearly whiteness which was seen to surround 

 the moon's disc ; the two clouds seemed, nevertheless, 

 continuous. 



This bow was twelve moons' breadth in length, and we 

 experienced no difficulty in distinguishing the various 

 colours. The red, green, and blue were seen to best 

 advantage at the middle of the arch, whilst their inter- 

 mixture with yellow and violet at each end of the bow 

 resembled the colours reflected from moonstones or pearly 

 shells : the violet was innermost, and the sharp boundary 

 line between it and the shiny white was very beautiful. 



The whole phenomenon lasted about four minutes, and 

 was totally difi'erent from the rather common corona' and 

 cloud edges seen at this season of the year, and which I 

 have been watching for some time past. 



There were no other clouds in the immediate vicinity of 

 the moon — indeed, the whole sky seemed at the time 

 remarkably clear — whilst the dark blue appearance of the 

 west might have had something to do with the unusual 

 appearance which I have endeavoured to describe. 



The prismatic edges of clouds are generally regarded as 

 a sign of stormy weather, and judging from what we have 

 experienced lately the phenomenon which we had the 

 privilege of watching amply justifies this conclusion. 



Portmadoc. W.\lteii Williams, M.B. 



PROPER MOTIOX OF CONSTELLATIOX CRSA MAJOR.- 

 To the Editors of Knowledge. 



Sirs, — At the foot of the article on the constellations of 

 Ursa Major and Ursa Minor which appears in the October 

 Number of K^■o^^xEDGE, it is stated that all the seven 

 principal stars in the former group have been found to 

 have a common proper motion. Is this correct ? In 

 Proctor's " Other Worlds" appears a diagram showing that 

 a and 17 are travelling in almost the opposite direction 

 across the line of sight as' compared with the other five. 

 I believe that the spectroscope also confirms this grouping 

 as regards their motion in the line of sight. If any recent 

 observations have tended to contradict Proctor's deduc- 

 tions, I should be very glad if you would give the informa- 

 tion in an early issue. L.iWKEscE P>. Tappenden. 



[Mr. Tappenden is quite right in taking exception to 



N. 



? 



Anxuai Pbopee lIoTioy. 



Mr. Reynolds' statement that "all the seven stars have a 

 common proper motion through space." As the accom- 

 panying diagram will show, e and ^ have almost exactly 

 the same proper motion, and / and 6 are similar in 

 direction. But the motion of p differs considerably from 

 that of the four above-named, and a and i; are moving, as 

 Proctor quite correctly stated, almost in the opposite direc- 

 tion. It is certain that these two do not belong to the 

 same system as the other five, and I scarcely think the 

 evidence warrants us in following Proctor, and asserting 

 the physical connection of all the five. 



The spectroscopic evidence is inconclusive. The Potsdam 

 results for the motion in the line of sight of thc-se stars 

 give practically the same motion of approach for /3, y, t, ^, 

 and •);, and a smaller motion in the same direction for a. 

 Dr. Huggins found about the same speed for all the five 

 stars, but found that they were receding from us. 



The proper motions adopted in the diagram are those 

 derived by Prof, .\mvers from his new redaction of 

 Bradley's observations. — E. Walter Maundeb.] 



♦ 



MACQUEEN'S BUSTARD (Otis Maeqweiti). 



Ox October 17th I was walking along the sea-bank at 

 Easington, Yorkshire, in company with Mr. Eagle Clarke, 

 the well-known ornithologist, and ilr. Bendelack Hewetson, 

 Jun. We all at once noticed a large bird flying low over 

 the fields like an owl, and being pursued by small birds. 

 It skimmed across a high bank and went down in 

 a field beyond. We immediately followed it, and on 

 arriving at the bank crept up to the top and cautiously 

 looked over. 'L'hero, in the middle of a stubble field, about 

 one hundred and twenty yards from us, was what we took 

 to be a great bustard. 



