3 88 



NA TURE 



\_Atigust 23, 1883 



regarding the transmission eastwards of barometric movements, 

 and in which he likewise alludes to simultaneous affections of the 

 barometer. Speaking of these latter he says: "As to the 

 cause of the e widely distributed simultaneous movements of the 

 barometer ... I have no evidence of any value. The most 

 natural idea is that a connection direct or indirect may be traced 

 between them and changes in the state of solar energy. ... I 

 have not a sunspot curve for the years under consideration, and 

 cannot therefore make the necessary comparisons." 



I may mention that simultaneous affections of atmospheric 

 pressure were fir t observed by the late John Allan Broun, and 

 that I have compared his instances with sunspot records. The 

 results of this comparison were published last year in the Pro- 

 endings of the Literary and Philosophical Socitty of Manchester. 

 I have not the volume here with me, but if my memory does not 

 deceive me an increase of pressure was found to be associated 

 with increasing unspots and a decrease of pressure with decreas- 

 ing sunspot . IJalfour Stewart 



Devonshire, Augut 17 



Dreaming 



Instances have lately been described in Nature of remark- 

 able formation or perversion of dreams at the instant of waking. 

 Allow me to offer you the following, which was vividly impressed 

 on my mind, and which I still remember with the utmost 

 accuracy : — 



In the summer of 1822, when an undergraduate of Trinity 

 College, Cambridge, I was permitted to reside in College rooms 

 during the summer long vacation. As fires were not wanted in 

 our sitting-room-, it was customary for each resident's bedmaker 

 or other officer to carry his water-kettle for breakfast and tea to 

 the College kitchen, and bring it back with water boiling. On 

 one occasion I had overslept my usual hour, and I dreamed a 

 dream. I was at the gate of a country farmyard well known to 

 me, and there came a long procession of horses, asses, oxen, 

 hogs, sheep, and all the animals usually to be found in a farm- 

 yard, followed by a north country drover with his plaid ormaude 

 crossed over his shoulder, who walked up to me and said, " Sir, 

 I have brought your cattle." In an instant I perceived and 

 actually heard (so intimately were the auditory sounds and the 

 i ntellectual interpretation intermixed) that my bedmaker was at my 

 chamber door calling to me, "Sir, I have brought your kettle." 

 The hearing had been confused ; there had been no reasoning]; 

 but there had been instantaneous vigour of creative imagination. 



An admirable instance of the same kind is described in the 

 last chapter of Scott's "Rob Roy." Scott appears to have 

 been in some measure a student of dreams. I refer with plea- 

 sure to the description of Fitzjames's dream, after a day of 

 labour and an evening of excitement, at the end of the first 

 canto of "The Lady of the Lake." A. B. G. 



August 18 



Thunderstorms and Aurorse 



I would like to ask if any observer has ever suggested a 

 possible connection between thunderstorms and the aurora ? 

 Last evening a very heavy shower, accompanied by much 

 lightning, passed to the north of this place. Other black clouds 

 were seen to the south and west, and at nine o'clock flashes of 

 lightning might be seen darting across the clouds in nearly all 

 directions. It was evident that the air was heavily charged with 

 electricity. Just before retiring, about midnight, I looked from 

 my window to see if a shower was s'ill threatened at this point. 

 I found the heavens quite clear except in the north, where a dark 

 mass of clouds still hung. At the eastern extremity of this 

 cloud-bank a rift several degrees wide commenced and extended 

 nearly to the north-western horizon. Frequent flashes of light- 

 ning lit up the edges of this rift, while beyond the clouds the 

 clear sky was seen to be brightly illumined by a steady auroral 

 glow. The glow continued nearly unchanged during the several 

 minutes which I watched it, and it was quite evident that it was 

 a genuine aurora, and not a reflection of the lightning flashes. Is 

 it not probable that the same electrical state of the atmosphere 

 which produces the thunderstorms may also cause the aurora, 

 and that the two phenomena may often occur together ? 



Lewiston, Maine, U.S.A., July 6 E. R. Chadbourn 



" Elevation and Subsidence " 

 QUOTING Prof. Geikie's "Text-book," Mr. Starkie Gardner 

 says : " Slrnta of se1iiie n tnry origin which have accumulated to 



thousands of feet in thickness, may be depressed deep beneath 

 the surface and brought within the influence of metamorphosis. 

 . . ." He continues : "This is an absolute admission that at 

 some depth, relatively not great, pressure converts solid into 

 viscous or fluid strata." A few lines further: "If the mere 

 pressure of overlying strata can anywhere or at any depth render 

 rocks molten or fluid, they will become molten or fluid wherever 

 the required pressure occurs." But is not the supposition the 

 exact reverse of what is really the case, viz. that not only does 

 pressure not liquefy rocks, but actually prevents their melting 

 at a temperature at which they would melt were the pressure 

 removed? Mr. Gardner himself admits this in the case of the 

 nucleus, i.e. when we come to very extreme pressures ; how then 

 can pressures of an intermediate order of magnitude have the 

 opposite effect? This is surely not the view of Prof. Geikie. 

 The passage quoted by Mr. Gardner from his work refers to the 

 fusion of roc' s by the high temperature found at great depths. 



If Mr. Gardner means to imply, as some of his expressions 

 strongly suggest, that the cause of the high temperature of the 

 interior of the earth is the pressure of the superincumbent rocks, 

 it would be interesting to know how he reconciles his theory 

 with the principle of the conservation of energy. Heat is energy, 

 pressure is force. Force can only give rise to a manifestation of 

 energy by acting through a finite distance, the energy manifested, 

 or " work done," being the product of the force and the distance 

 through which it acts. If either factor be zero, the other not 

 being infinite, the product is also zero. The application to the 

 case in hand is too obvious to require statement. 



Trinity College, Cambridge, August 4 F. Young 



Insects and Flowers 



Having this morning received the last numher of the Pro- 

 ceedings of the Linnean Society containing Mr. A. W. Bennett's 

 and Mr. Christy's observations on the constancy of insects in 

 their visits to flowers, it occurred to me, after reading only the 

 first page, to see how insects behaved in my own garden, where 

 there is a great variety of plants. I had not read the conclu- 

 sions of either author, and had no preconceived opinion on the 

 subject. The results were noted at once, and were as follows : — 



1. P. rapa (small white butterfly) on a bed containing white 

 and rose-coloured double and single stocks al-o, scarlet pelar- 

 goniums and pink phlox ; visited single white stocks only, going 

 all round the circle in which they were planted ; then flew off, 

 made a dive at a white phlox, but did nit alight, hovered 

 about some little time without alighting, and finally went out of 

 sight. 



2. Same species ; two individuals on a bed of scarlet pelargo- 

 niums edged with sulphur-coloured pansy (? Viola lutea, var.). 

 One butterfly kept to the pelargoniums, paying repeated visits ; 

 the other did the same with the pansies. 



3. Same species on a bed of dark purple pansies with bright 

 yellow eye, crossed and edged with orange French marigolds. 

 Two individuals visited both plants promiscuously, but the mari- 

 golds oftenest. A P. napi (green-veined white butterfly) did 

 the same. Vanessa urtica (small tortoiseshell butterfly) on the 

 same bed visited only the marigolds. This species seems re- 

 markably partial to yellow. 



4. P. rapic on a bed of scarlet pelargonium and pale blue 

 pansy with dark centre and pale yellow eye intermixed. Visited 

 the pansies very often ; the pelargoniums once only during 

 observation. 



5. Same species on Lythrum salicaria remained a long time 

 visiting different spikes, then flew round, neglecting all other 

 flowers till it found another plant of the same kind, which it 

 continued on as long as I watched it. 



Bombus lucorum. This bee was very abundant, both workers 

 and females. I watched them on a mixed bed which contained 

 Pentstemon barbatum (dull scarlet), African marigolds (yellow), 

 Antirrhinum ma/us (crimson), pansies, both dark purple and 

 yellowish white, and mignonette. The favourite plant was the 

 pentstemon, especially with the 9 . They got at the nectary 

 by inserting the proboscis in a hole cut near the base of the 

 corolla. The next favourites were the marigolds. One indi- 

 vidual confined himself exclusively to the antirrhinum. In 

 one case only did I observe a bee to change from one kind of 

 flower to another, though I looked out especially to see if they 

 did so. This was a bee which went from a crimson petunia to 

 an antirrhinum of very nearly the same shade of crimson. 



