March 21, 1889] 



NATURE 



493 



sun. The first great departure from prevailing opinions 

 is the view that the sun is in a tranquil state, and is in no 

 way subject to the violent storms which are commonly 

 believed to disturb it. The stratified character of the 

 solar atmosphere is set forth as evidence of this tranquil 

 state. Dr. Brester believes that the apparent motions of 

 the protuberances are not real, but simply indicate the 

 displacement of the luminous condition brought about 

 by chemical combinations in tranquil matter. This he 

 believes to be quite consistent with the observed dis- 

 placements of the prominence lines, and we see no reason 

 to differ with him. 



The next important divergence from prevailing ideas 

 is the suggestion that pores, spots, and faculas are all at 

 exactly the same temperature because they are at the 

 same level. The experiments of Spoerer and Langley 

 have shown that the spots emit less heat than the other 

 parts of the photosphere ; but Dr. Brester states that 

 this is not due to a difference in temperature, but to a 

 difference of emissive power. He believes that spots 

 are formed by the vaporization of the photospheric mat- 

 ter in the regions where they are formed, the luminosity 

 being reduced, whilst the temperature remains the same. 

 On this supposition, the photosphere bears the same 

 thermal relation to the spot that ice does to the water 

 formed as it melts. 



The forms of the spots he believes to be due to the 

 increase of pressure caused by the volatilization of the 

 photospheric matter, the conical form being due to the 

 fact that the nearer the centre the greater the resistance 

 to the expansion. 



That faculas should precede spots Dr. Brester states 

 to be essential to his hypothesis. They indicate the 

 places where increased condensations are taking place 

 prior to the " eruptions of heat " which will produce 

 spots. 



For an explanation of the periodical phenomena, and 

 the increased angular velocities of spots near the equator, 

 Dr. Brester assumes that, while the photospheric surface 

 which we see is spherical, the different layers of the atmo- 

 sphere must be ellipsoidal, owing to the rotation of the 

 sun. He admits that this state of things is not easy to 

 explain, but states that it is sufficient to know that the 

 fact exists. This being taken for granted, the varying 

 periods of rotation in different latitudes is not difficult to 

 explain. For since the photospheric matter is formed by 

 the condensation of the vapours of the ellipsoidal layers, 

 the particles in equatorial regions have to descend a 

 greater distance towards the centre than those in the 

 same layers near the Polar regions ; and since the linear 

 velocity remains the same during the descent, the angular 

 velocity is increased, and is increased more at the equator 

 than away from it. Since the spots lie in the photosphere, 

 they thus indicate an increased angular velocity in equa- 

 torial regions. It will be seen that this explanation is 

 much akin to that suggested by Mr. Lockyer,* differing 

 from it mainly in giving the whole photosphere the addi- 

 tional velocity, whereas, according to Mr. Lockyer's view, 

 only the spot-forming material partakes of the added 

 angular velocity. 



The relation of spot spectra to the eleven-yearly period 

 observed by Mr. Lockyer is also partially explained. 

 According to Dr. Brester's view of the solar economy, the 

 photosphere must have a special composition in each 

 latitude, and since the latitudes of the spots vary with the 

 period, the spectra would also vary with the period. The 

 exact nature of the change — namely, from lines of iron and 

 other known substances at minimum to unknown lines at 

 maximum -is not explained. 



The similarity of the spot zones on both sides of the 

 equator, according to Dr. Brester's view, is due to the 

 fact that the same atmospheric layer meets the photo- 

 sphere in equal latitudes on opposite sides of the equator.. 



' " Chemistry of the Sun," p. 424. I 



The slight differences which do exist are regarded as 

 simply the effect of chance, since an "eruption of heat" 

 may either produce one large spot or several smaller ones. 



Dr. Brester also attempts to explain the cause of the 

 eleven-yearly period, but his explanation is difficult to- 

 follow. Broadly speaking, his idea is that during eleven 

 years the integrated effects of the various chemical com- 

 binations which have taken place are such as to very 

 nearly restore the conditions which had existed at the 

 commencement of the period. Slight differences would 

 be produced each time, so that after a long interval, well- 

 marked differences might be expected. 



Although the theory explains many of the phenomena 

 observed, an explanation of many more is still required. 

 Thus, although it is not difficult to understand the 

 absence of spots at the equator, the cooler layers there 

 being at the greatest distance from the photosphere, we 

 should be led to expect the greatest number of spots in 

 polar regions, where the atmosphere in the neighbourhood 

 of the photosphere is coolest, and where, therefore, 

 chemical combinations would be most likely to take 

 place. The question of the corona is reserved for a 

 future essay, but Dr. Brester is confident that it will pre- 

 sent no great difficulty. He also hopes to satisfactorily 

 explain the phenomena of comets' tails, the zodiacal light, 

 and the variability of Jupiter and his satellites. 



In conclusion, Dr. Brester states that his theory, so far 

 from being at variance with the laws of chemistry and 

 physics, really strengthens them, and that it is not dis- 

 cordant with the observed facts. At the same time he 

 admits that the difficulty of comprehending it in detail 

 will prove a great drawback to its acceptance. 



A. Fowler. 



THE RABBIT PEST. 

 IX/TR. W. RODIER, of Tambua, Cobar, New South 

 iVl Wales, has forwarded to this Society a printed 

 sheet, containing, as it appears to me, by far the best 

 suggestion yet made for the extermination of rabbits — a 

 subject to which my attention has been repeatedly called 

 by various correspondents in the Australian colonies, 

 where, as is well known, the damage done by these 

 animals is enormous. Mr. Rodier states that his plan 

 has been in operation at his station in New South Wales 

 for about eight months "with the utmost possible suc- 

 cess," and has cleared the country of rabbits. It is a very 

 simple plan. Ferrets and nets are used in the usual way 

 to capture the rabbits, but while all the females taken are 

 destroyed, the males are turned out again uninjured. 



The results of this mode of operation are that the male 

 rabbits, as soon as they begin to predominate in numbers, 

 persecute the females with their attentions, and prevent 

 them from breeding. They also kill the young rabbits 

 that happen to be born ; and even, as Mr. Rodier asserts, 

 when they largely predominate in numbers, " worry the 

 remaining does to death." 



This is all strictly in accordance with what we know 

 takes place under similar circumstances in the case of 

 other animals, so that we can readily believe it to be 

 likely to happen. 



The ordinary mode of trapping, as Mr. Rodier points 

 out, is more likely to increase the number of rabbits 

 than to diminish them. For reasons which he clearly 

 explains, more buck rabbits are always killed by the 

 trappers than does. Thus the does predominate in 

 numbers, and, a few bucks being sufficient for a large 

 number of does, are perpetually breeding and increasing 

 the stock. 



The plan advocated by Mr. Rodier is so simple and 

 easy that I cannot doubt it will be widely followed when 

 known. No disease that might otherwise cause injury 

 is introduced, no other noxious animal is proposed to be 



