130 



KNOWLEDGE 



[June 1, 1896. 



Hcttfts. 



[The Editors do not hokl tliemselvcs responsible for the opinions or 

 statements of correspondents.] 



MIRA CKTI. 



To the Editors of Knowledge. 



Sirs, — A miixirautn of e Ceti, Mira, was predicted 

 (Co)iiit(iiiion to the Ohscrratori/) for ]HS)5, December 9tli. 

 But as its miniimim occurred in October a search for it 

 was not bogiHi until late in November. Using a Lemaire 

 field-glass of twenty-four lines, I succeeded in linding it 

 delinitoly, December (Jth, and thenceforward to date it was 

 followed up assiduously without the loss of a single night 

 upon which an observation of fair value could bo obtained. 

 The season has been unfavourable for such work, not only 

 in this latitude but elsewhere throughout the States. 

 The following estimates are the results of my best en- 

 deavours ; — 



These figures show a maximum for February 1.5th, or a 

 day or two before, and that the star reached this phase 

 some sixty days later than the predicted date, and that its 

 brightness was a magnitude less than the traditional light. 



Comparison stars used:— y Ceti, 3'CO magnitude; a 

 riscium, 3-9; i, 4-2 ; V, 5-06; GO, 5-00; 70, 5-62; 71, 

 (i-55 ; D, C-U2 ; H, 7-80 ; N, 8'12 ; all in Cetus. 



R Leonis was again forty days ahead of the predicted 

 maximum; magnitude only Gi January 10th. 



David Flaneey. 



Memphis, Tenn., U.S.A. 



18th March, 189C. 



To the Editors of Knowledge. 



Sirs, — On several occasions between the 7th and 26th 

 December last I could just catch a glimpse of Mira Ceti 

 with the naked eye by close watching and oblique vision. 

 On the 29th December it was not thus visible to the 

 naked eye, on account of the bright moonlight. Cloudy 

 weather interrupted observations until January Gth, 189G, 

 when Mira was readily visible to the unaided eye as a fourth 

 magnitude star, being almost exactly equal with S Ceti, 

 and of a deep orange colour. 



On January 10th and 11th it appeared to be a little 

 brighter, and on the iHth I estimated it as but a little less 

 bright than y Ceti. Cloudy weather intervened until 

 February 7th and ilth, when Mira was about equal with 

 y Ceti. After this it appeared to gradually decrease, and 

 on February 23rd was about the same magnitude as S Ceti. 



Alta, Iowa, U.S.A., David E. Hadden. 



March IGth, 1806. 



SUN HALO. 

 To the Editors of Knowledge. 

 Sirs, — Last year I was with a party going through 

 Palestine and Syria. On Saturday, the 20th of April, we 

 stopped for luncheon at 11.30 a.m. on the plain a few 

 miles outside of Damascus. After luncheon, at mid-day, 

 we were suddenly surprised by a noticoable sight, which 

 was very strange to us, and of which none of us could 

 furnish an oxplanation ; it was a triple rainbow. First, 

 there was a complete rainbow all round the sun, with the 

 usual colours, the red inside ; second, to the south there 

 was a partial rainbow, part of a circle, concentric with the 

 circle round the sun, the red inside — this being evidently a 

 rellection from the other ; and, thirdly, there was another 

 complete circle, but without the colours of the rainbow — 

 just a broad plain ring, much like a lunar rainbow in 

 appearance, this circle lying to the north, with an inclina- 

 tion to the west, though not quite north-west, its circum- 

 ference running over the centre of the sun. All three 

 were visible at the same time, and there was no rain. 

 I should be glad to get an explanation of this curious 

 phenomenon, and hope the matter will excite the interest 

 of some readers of Knowledge. Heluis. 



[With regard to the optical appearance here described, 

 the fact of the bow being roimd the sun, and the additional 

 fact of the red colour being inside, are quite sufficient to 

 determine the phenomenon as a halo ; not a rainbow, but 

 a bow generated by the direct transmission of light rays 

 through ice crystals. 



The other, i.e., the second imperfect bow, also with red 

 inside, was clearly enough another halo, as it had the sun 

 also for its centre. The fact of the colours being similarly 

 arranged also shows it to be a halo, which commonly 

 has a red or an orange tint inside, with a bluish band 

 outside. I take it, for this very reason, to be not a reflection, 

 but a fresh halo with originating particles of a different 

 refracting angle, and consequently of a different radius. 



The circle resembling a lunar rainbow, which passed 

 through the sun's disc, is, without doubt, a " halo of ninety 

 degrees," an unusual form of halo, which owes its origin 

 to the reflection of light from the pyramidal ends of snow 

 crystals as they hang down towards the earth. A myriad 

 of these, with a bright sun, produce an apparently con- 

 tinuous band which spans the heavens, the sun being in 

 the circumference. — Samuel Bakber.] 



TIDE OF THE RIVER WYE. 

 To tJie Editors of Knowledge. 

 Sirs, — Would the October, 1883, tide on the Wye be the 

 result of the Krakatoa eruption ? The question only 

 suggested itself to my mind while reading the fascinating 

 paper by Rev. E. Rattenbury Hodges in the December, 

 1895, Number of Knowledge. The time distance between 

 the eruption and the tidal rise would be between seven and 

 eight weeks (August 27th to October 17th). Is this about 

 the time the great wave would take to reach our shores ? 

 The tide was phenomenal. F. H. Worsley-Benison. 



[In reply to Mr. Worsley-Benison's interesting question, 

 I have no hesitation in saying that I cannot consider the 

 Krakatoa eruption to have had anything to do with the 

 high rise of the Wye in October, 1883, which was a tidal 

 rise, the time of which, apart from its remoteness from the 

 east side of the Indian Ocean, shows it to have been part 

 of the great tidal wave due to lunar and solar influence. 



A seismic wave is one caused by a volcanic eruption ; 

 although it may reach coasts at a great distance ('/' tlwre is 

 no intereeninij land, it is non-coincident with the cosmic 

 tidal wave. — J. Logan Lobley.] 



