528 



NATURE 



\April 19, 1877 



during warm sunny days in winter, and again disappearing on 

 the return of cold. This fact it is certainly very difficult to 

 account for on any other supposition. Argyll 



Argyll Lodge, Kensington, April li 



" In your letter received last night you tell me of an article in 

 Nature the author of which seems to deny that swallows ever 

 hibernate, and asserts that no one has yet testified to the fact 

 from his own personal observation. That, however, is a mis- 

 take for I have stated and I now repeat that I have seen swallows 

 in large numbers hibernating. The circumstances were these :— 



"About twenty-five miles south of Teheran, the capital of 

 Persia, there is a village called Kenara-gird near which is a 

 stream of brackish water running in a deep bed with nearly 

 perpendicular banks some forty or fifty feet high. Being largely 

 impregnated with salt this stream is rarely if ever frozen^ and in 

 frosty weather is resorted to by flights of wild ducks. During a 

 frost of unusual severity I went from Teheran to Kenara-gird, 

 accompanied by Sir Henry Rawlinson, for the purpose of duck- 

 ^hcotine, the severity of the frost promising good sport Having 

 slept at' the village we next morning followed the downward 

 course of the stream along the north bank, and had proceeded 

 about a mile, I should think, when we came to a pkce 

 •where there bad quite recently been a small land-slip. Ihe 

 brink of the bank to the extent of perhaps twenty feet 

 In length, and ten or twelve broad in the middle, tapering 

 off to each er.d, had slipped, but had not fallen down the 

 bank. Between this detached portion and the perpendi- 

 cular face about ten feet high, from which it had broken 

 off we saw, to our great surprise, a number of swallows, 

 not less, I am sure, than twenty or thirty, lying, as I at 

 first supposed, dead, but on taking up ore of them _ 1 

 fouDd that it was alive but dormant ; it was warm and its 

 breathing was quite perceptible. I examined a considerable 

 number, and found that they were all alive and breathing, but 

 none of them gave any sign of consciousness. My attention was 

 then attracted to the perpendicular face on our !eft, from which 

 the slip had broken off, and which was perforated by a vast 

 number of holes each about the size of a rat -hole. On looking into 

 such of these as I was tall enough to see into, I fouun in ail ot 

 them swallows in the same dormant state. I was able with 

 finger and thumb to pull out swallows from several of these 

 hole': and in each case found that the hole which penetrated 

 horizontally a considerable way into the bank, contained more 

 swallows in the same condition. In no case did I see one lying 

 on another— they were all lying singly with their heads inwards, 

 each head touching the tail ot the bird befcre it. How far these 

 holes penetrated into the bank, or what number of swallows each 

 contained I did not ascertain, but it is plain that the ongmal 

 entrance to thrse dormitories, must have been in the external 

 face of the portion that had sbpped, which as I have stated, was, 

 in the middle, from ten to twelve feet thick. The holes in the 

 undisturbed portion may probably have been of equal or greater 

 length, and if so the number of swallows hibernating there must 

 have amounted to many hundreds." 

 Villa Poralto, Cannes, April 6 



The Swallows and Cuckoo at Menton 

 The swallow that arrived here on March 19 remained solitary 

 until April 5. Early that morning a second arrived and entered 

 the same room as the first. I saw them flying about together m 

 the forenoon, and these two remain the only feathered occupants 

 of that chamber. In the afternoon of the same day, however, 

 a party of ten arrived and distributed themselves among the 



houses. . • 1 ii. 



Madame Valetta, of whom I spoke m my previous letter 

 (Nature, vol. xv., p. 488), assures me that not during the last 

 fifty years has one swallow preceded its fellows by so long an 

 interval as this year ; but perhaps it is only that her attention 

 has not been drawn so much to the subject. It is certain, how- 

 ever, that unless more are yet to come, the swallows are this 

 year fewer than ordinary by more than one-half. The opinion 

 cf the natives is that they have perished at sea. 



I heard the cuckoo for the first time this year on April i. 

 But a lady had to'd me that she hsd heard it nearly a week 

 before. Douglas A. Spalding 



Cab'roile?, pres de Menton, France, April 13 



Greenwich as a Meteorological Observatory 



The facts of observation appealed to by Mr. Eaton with the 

 vipw nf nrovinii that Greenwich is. from artificial causes, more 



than half a degree warmer than the south-east of England gene- 

 rally, and is therefore not a suitable place for a meteorological 

 observatory of the first order, evidently call for a closer 

 critical examination than they have yet received. If from the 

 sixteen stations within a radius of sixty miles from the metropolis 

 given in the paper on ** The Temperature of the British Islands," 

 we omit those which are clearly inadmissible for the comparison 

 with Greenwich owing to their position or to the short time 

 during which observations were made, there remain the follow- 

 ing eight stations as suitable for comparison :— Cardington, 

 52° 7' lat. N, ; Royston, 52" 2' ; Colchester, 51" 53' ; Hartwell, 

 51° 49; Oxford, SIMS'; Great Berkham=tead, 51^45'; Chat- 

 ham, 51° 23'; and Aldershot, 51° 15'. The mean temperature 

 of these eight stations, allowing for elevation, is 5o°-6, and the 

 mean temperature of Greenwich, 5i°-i, results substantially 

 agreeing with those given by Mr. Eaton. 



It is necessary, however, to observe that the mean posi- 

 tion of these places does not agree with that of Greenwich. 

 Thus while the latitude of Greenwich is 51° 28' north, the mean 

 latitude of the eight stations is 51" 45'. o' 0° 17' farther north, 

 their true mean position being about two miles due north of St, 

 Albans. For this difference in latitude a correction of fully 0° -2 

 is required, judging from the position of the isothermal lines. 

 The figures then stand thus : mean temperature of Greenwich, 

 51°- 1 ; of the eight stations, 5o°-8. On comparing the monthly 

 means of the eight stations with those of Greenwich, it is seen 

 that the residual excess of Greenwich is all but wholly occa- 

 sioned by the high mean temperatures of June, July, August, 

 and September, which are in each case o'-g higher than the 

 means of the eight stations, these eight stations being nearly all 

 outside or on the outskirts of the patch of high temperature 

 around London during the summer months. It follows that the 

 o'"3 of excess of annual temperature at Greenwich over the eight 

 stations is accounted for by the higher temperature of four out of 

 the twelve months, and consequently cannot be due to artificial 

 sources of heat in London, such as the consumption of fuel. 



When drawing the isothermals of the British Islands seven 

 years ago, no district of Great Britain occasioned so much 

 -trouble and uncertainty as the south-east of England, owing to 

 the meagreness of the materials available for the purpose. Smce, 

 howevert immediately to westward, the mean temperature of 

 Oxford was seen to be 5o°-4> Aldershot 51" "2, and Osborne 

 5X°'8, it was inferred as the most probable state of the case that 

 the "mean temperature increased southwards over the south-east 

 of England in the manner indicated by the annual isothermals 

 accompanying the paper. This supposition was confirmed by 

 the temperatures at Colchester and Chatham, the only two sta- 

 tions furni-hing satisfactory data on the point, for <vhile at Col- 

 chester, for instance, the mean temperature was o" 5 lower than 

 that of Greenwich, no less than o"-4 of this difference was due 

 to the lower temperature of the east coast at Cokhester as com- 

 pared with Greenwich during the five months beginning with 

 December, when the temperature in the south of England in- 

 creases from east to west. 



The coast stations of the Channel could not be considered as 

 furnishing authoritative evidence on the question, owing to the . 

 irregular distribution of their temperature, which seemed to in- 

 dicate certain obscure and ill- understood causes in operation 

 modifying the climates of that coast. The force of this remark 

 will be apparent " from the following mean temperatures:— 

 Helston, 53°-9 ; Truro, 52° -2 ; Torquay, 5i°-6; Sid mouth, 51 "i ; 

 Bournemouth, Si^'S ; Ventnor, 52°-4 ; and Worthing and East- 

 bourne, both 50° 7. It is perhaps scarcely necessary to renaa^ 

 that it would be a mistake to attempt to draw any conclua 

 from differences of mean temperatures of different statU 

 amounting to o°-3 and under, seeing that the English^ obserj 

 tions generally were made with thermometers in protecting-bol 

 quite open on one side, and therefore exposed in varying deg^ 

 to indirect radiation from walls and other objects. 



While Mr. Eaton has thus failed to prove from past obset 

 tions that the consumption of fuel and the massing together 

 living beings in London has raised the mean temperaturej 

 Greenwich Observatory to the extent of half a degree, or ind| 

 to any appreciable extent, above that of the south-east of El 

 land generally, it might nevertheless be well, seeing the quest* 

 has been raised, to do something towards definitely answenog 

 by instituting at Greenwich and at about a dozen stations dis 

 buted over the south-east of England, observations of the temj 

 rature of the air, strict uniformity being secured by employi 

 the same pattern of thermometer-box and by placing it und 

 the same conditions at each place as regards height above « 



