THE SECOND WINTER MEETING. XXXV. 



moon's axis, the general appearance was most striking and beautiful, the light of 

 the cross being nearly equal to that of the lunar surface. It need hardly be said 

 that the phenomenon was not astronomical, being, in fact, wholly atmospherical, 

 and that it arose from the reflection of the lunar light from the particles of 

 vapour, which must have been very dense at the time. Why the appearance 

 took the form of a cross is not clear, and even at the time would not have been 

 disclosed. In that respect it seems a meteorological mystery. 



Mr. Whitmell, B.A., one of His Majesty's School Inspectors, has skilfully 

 devoted much attention to the origin of lunar halos. He says that they are due 

 to the reflection of lunar lights from the particles of ice in the upper regions of 

 the air, and, when there is colouring, it is due to the analysis of the light, on the 

 same principle as the rainbow. This explanation commends itself to all investi- 

 gators. He also says there are two principal halos, the smaller distant 22 from 

 the light-giving orb, and the larger distant 46 ; both have their outer borders 

 green, their inner red, and both have the sun or moon for their centre. These 

 remarks already associate mock suns and moons, rainbows, and coloured arcs 

 with halos, forms being modified by atmospheric conditions. It may be noted 

 that the cruciform aspect is very rare, and may be produced in a similar manner 

 as the striking sun -pillar, which also is seldom seen. 



The following items are taken from an old encyclopaedia of date 1813. They 

 are curious, if not valuable, additions to the literature of the subject. The 

 writer states that Huygens supposed that writers on the theme generally believe 

 that halos or circles, more or less coloured, were formed by minute grains of 

 hail. Huygens fully endorsed this theory, and illustrates it by drawings of the 

 formation. Huygens was a very careful observer of natural phenomena, and 

 his ideas and observations are deserving of all credit. Newton's theory of halos, 

 as given in his work on optics, &c., favours the theory that halos are caused by 

 the refraction and reflection of light from the sun or moon. He says the more 

 equal the globules of ice or vapour may be, the more crowns of colour and the 

 more lively the tints. There are several ways of exhibiting these phenomena. 

 The flame of a candle placed in the midst of a steam in cold weather, or placed 

 at a distance from a window which has been breathed upon, will also show slight 

 coloured halos. Also a quantity of water thrown up against the sun or moon will 

 show halos a kind of mock rainbow. Musschenbiok, a German author, observes 

 that, when the windows of his room were covered with a thin plate of ice, the moon 

 seen through it was surrounded with a variously coloured halo, and, on opening 

 the window, the apparition was entirely gone. Of course, all these experiments 

 must be patiently and perseveringly performed, and may be almost endlessly 

 diversified, according to the knowledge and skill of the performers. 



EXHIBITS. 

 BY THE PEESIDENT : 



A series of deeds dating from the reign of James I., with a few of earlier date, 

 from Eichard II. 



