Feb., 1905.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



37 



humidity and vibration are quite inapplicable, and we 

 must search for some further cause. Some people 

 have vaguely ascribed the results to electrical mani- 

 festations, but ignorant people have a way of imputing 

 (often, perhaps, with some truth) all unaccountable 

 phenomena to electricity. 



However, the subject is an interesting one and well 

 worth careful investigation, and as Prof. Wertheimer 

 has kindly promised to send us the results of his investi- 

 gations, we shall look forward with much interest to 

 the report. The Times suggests that " half-a-dozen 

 men of ordinary ability, powers of observation, and 

 common sense, could settle the whole question by 

 putting half-a-dozen ' water-finders ' to the test." If 

 they clearly proved the dowsers at fault the whole 

 question might be fairh- settled, but if the water should 

 invariably be found where predicted, the question would 

 be very far from being settled. We would suggest 

 that a beginning might be made, as it were, at the 

 other end; that is to say, to conduct some careful 

 scientific observations as regards the hygrometric, 

 thermometric, electrical, and vibratory conditions of 

 the earth and air at a spot beneath which a spring of 

 water was known to exist. If peculiar conditions were 

 found to exist, then we would know that there might, 

 after all, be something in human " water-divining." 



CORRESPONDENCE. 



TKe Great Red Spot of Jvipiter. 



To THE Editors of " Knowledge." 

 Gentlemen, — In your note on p. 13 of the current number 

 of " Knowledge & Scientific News," you are good enough 

 to refer to some recently-published results by the writer rela- 

 tive to the motion of the above spot. May I, however, point 

 out that my observations and conclusions are in agreement 

 with those of Mr. Denning, and that they do not really " seem 

 to indicate very different results," as stated in your note ? 

 The rotation period found here for the red spot in 1902 is 

 g h. 55 m. 39'56 s., and for 1903 it is 9 h. 55 m. 4i"52 s. 

 Mr. Denning's figures for the same two years are g h. 55 m. 

 3g'4 s. and g h. 55 m. 40"8 s. re.^pectively (see the Observatory, 

 :go4, p. 343). It will be seen that both Mr. Denning's obser- 

 vations and those made here indicate a distinct increase in the 

 length of the rotation period. The shorter period of g h. 55 m. 

 38'6 s. ascribed to Mr. Denning refers to the first seven or 

 eight months of igo4, and seems to be due to further vagaries 

 in the motion of this truly remarkable spot. 



Mr. Denning, I believe, observed the great hollow or bay in 

 the south equatorial belt of Jupiter, nearly opposite to the red 

 spot, whilst the spot itself was observed here. The periods of 

 time over which the observations extended are also probably 

 not exactly the same. These circumstances will probably 

 account for much of the not very large differences between 

 our figures quoted above. I believe that a shortening in the 

 length of the rotation period of the red spot for the first seven 

 or eight months of last year, similar to that pointed out by 

 Mr. Denning, will also be shown by my observations, but 

 these are still in progress, and I am anxious to avoid, as far as 

 possible, making any examination or comparison of the results 

 obtained until the close of the present apparition of Jupiter, so 

 as to avoid being biassed as much as possible. The Rev. 

 T. E. R. Phillips confirms, however, the more rapid motion of 

 the spot in the first seven or eight months of igo4 (sue Journal. 

 B.A.A., Vol. XV., p. 28). How far these somewhat curious 

 changes in the motion or drift of the red spot are real, and how 

 far they may be only apparent, and due to the changed sur- 

 roundings of the spot, must be left to future consideration. 

 A. Stanley Williams. 

 20, Hove Park Villas, Hove, 

 January 9, 1905. 



ASTR.ONOMICAL. 



A Sixth Satellite of Jupiter. 



During December last, Professor Perrine, of the Lick Obser- 

 vatory, suspected the existence of a new satellite, but it was 

 not till early in January that observations made with the 

 Crossley reflector confirmed his suspicions. The distance 

 from the planet was much greater than that of any of the 

 other satellites, being then 45'. The motion of the satellite 

 was reported to be retrograde, presumably referring to its 

 apparent motion in the sky, and not to its orbital motion. It 

 has a magnitude of 14. 



* * * 



Observations of Meteors- 

 Systematic observation of meteors was conducted at 

 Harvard Observatory on November 14-15, four observers 

 watching while an assistant wrote down the records. In this 

 way 275 meteors were recorded. Though the heads at the 

 time of explosion were usually blue or white, in two cases at 

 least they were red or orange, which diff'erence in colouring is 

 ascribed by Professor Pickering to variation in chemical 

 constitution. Elaborate preparations were also made to 

 photograph the meteors, but only two trails were recorded on 

 the negatives exposed. 



» * * 



Eclipse Expeditions. 



Three expeditions are being arranged in connection with the 

 Lick Observatory for observing the total eclipse in .August. 

 The cost of them will be borne by Mr. William H. Crocker. 

 One is to go to Labrador, a second to Spain, and a third to 

 Egypt. Photographs will be taken to endeavour to ascertain 

 the existence of an inter-mercurial planet in addition to the 

 photographing of the corona. 



Death of Mr. Crossley. 



The announcement of more important discoveries by 

 means of the Crossley Reflector at the Lick Obscrvatorj' has 

 just been followed by that of the death of the donor of that 

 great instrument, Mr, Edward Crossley. the Chairman of a 

 great carpet manufacturing firm of Halifax, Yorkshire. 



BOTANICAL. 



By S. A. Skan'. 



The New Zealand Institute has lately issued Vol. XXXV. of 

 its Transactions, which, like many of its previous ones, con- 

 tains some important and extremely interesting papers relative 

 to the botany of New Zealand and the neighbouring islands. 

 We are reminded in Mr. W. W. Smith's communication on the 

 "Plants Naturalised in the County of Ashburton" of the 

 extraordinary number of alien species which have established 

 themselves in New Zealand. In Ashburton the naturalised 

 species number 368, of which as many as 95 per cent, belong 

 to the Scandinavian flora. Many of our familiar weeds are 

 abundant in this distant Colony, where they often flourish to 

 an extent rarely known in their native country. A thistle 

 (Cariiuiis lanccolatits), Mr. Smith tells us, grows so \igorously in 

 Ashburton that some places are rendered impassable, even on 

 horseback. The late Professor Kirk, writing in Vol. XXVIII. 

 of the Transactions, estimates the number of naturalised 

 species in New Zealand as over 500, and he described the 



