Oct. 16, 1879] 



NATURE 



577 



our standard of reference for air temperature until a further j 

 reduction of the photographs shall enable us to extend the period 

 and so further improve them. The mean temperature of Green- 

 wich, according to Table 77, is 49°"72. , , ^ , 



The mean temperatures of Table 52 are also deduced from 

 the photographs, without correction for omitted days; they 

 serve to show the climatic variations in different years : if desired, 

 the effect of the omitted days could be readily determined. Here 

 the mean temperature comes out 49° '69. 



The table of mean air-temperatures for the period 1847-1873, 

 deduced from eye-observations (Table 125), to which particular, 

 attention is drawn, p. 526, is naturally of secondary importance, 

 and really owes its introduction into the volume partly to 

 accident. It was thought desirable in preparing for press the 

 deductions from the photographic records, to add, in the same 

 volume, but in a separate section, a collection of resiilts of the 

 observations of the earth-thermometers for the period 1847- 

 1S73, and a table showing the mean air-temperature during the 

 same period seemed a proper accompaniment to these results. 

 Now the photographs had been discussed only for the period 

 1849-1868, and, as there were already existing mean temperatures 

 for the longer period, 1847-73, deduced from eye observations 

 (by use of Mr. Glaisher's corrections), these temperatures were 

 taken for comparison with the earth-thermometer results. The 

 expression " accurate mean temperatures " (last line of extract, 

 p. 526) was never intended to indicate that Table 125 should 

 supersede Tables 52 and 77, but simply to explain that the 

 air temperatures were mean temperatures as distinguished from 

 the noon temperatures of the remaining tables of the section. 

 Further it is indicated in a sentence not quoted, but forming por- 

 tion of the paragiaph from which the extract already referred to 

 is taken, that the eye observation series was adopted for this 

 section because photographic results were not available for the 

 whole period. It may be here explained that employment, for 

 reduction of the eye-observations, of the corrections for diurnal 

 range, &t., given by the photographic records, produces values in 

 harmony with the photographic values, and corrections so derived 

 .".re now used in the reduction of eye-observations for immediate 

 r.se. But Table 125, as it stood, fulfilled the object for which it was 

 inserted, that object being rather to exhibit variations of tempera- 

 sure. No argument founded on the absolute temperatures shown 

 by the earth-thermometers has much significance, because we are 

 imable to test their index errors. In fact, the true value of the 

 •.vhole collection of tables in the earth-temperature section con- 

 •i-ts, not on their exact indication of absolute temperature, but 

 on the information which they afford in regard to comparative 

 changes of temperature, the retardation of temijerature, and 

 generally the propagation downwards of surface-waves of tem- 

 perature. 



In the last paragraph of the notice attention is directed to 

 what is called the "somewhat rough method" adopted in 

 reducing the barometric observations to 32°. This erroneous 

 idea may have, perhaps, been encouraged by the ch-cumstance that 

 in the Intro<luction no mention appears to have been made of the 

 fact that the temperature of the underground apartment in which 

 the photographic barometer is placed is almost uniform. Con- 

 sidering this in connection with the construction of the apparatus, 

 in which (as fully explained in the Introduction) the register 

 depends on the height of the mercury in the lower tube of a 

 syphon barometer, and is influenced by the expansion of some four 

 inches only of the mercurial column, it will be understood that 

 the effect of temperature (change of temperature) in a period of 

 f.venty-four hours (the extent of one sheet) is not perceptible. 



In the third and fourth lines of the paragraph, on p. 526, 

 commencing " From this table," it would seem that the word 

 •' excess" should be "defect." William Ellis 



Royal Observatory, Greenwich, October 7 



Saturn's Dusky Ring 



I WRITE to call the attention of observers to the present 

 appearance of the inner dusky ring of Saturn. Although the 

 ring is not very open, only jermitting that portion near the ends 

 to lie seen on the nights of the 9th and nth of this month, using 

 a portion of a large reflector sufficient only to show Knceladus 

 clearly, it was most prominent, and not to be overlooked. It had 

 the appearance of being covered with bright points, such as a 

 rough dusk paper touched lightly with chalk would give ; that 

 part in front of the ball being dark, and showing as a fine dark 

 line acro.ss, equal in width and shade to the shadow liencath, so 

 that the narrow part of the whole ring appeared on the face of 



the^lanet as if bounded by two fine parallel dark lines. The 

 wide and the narrow division at the ends of the ring were very 

 plain. 



Not having seen this dusky ring before, I can only go by the 

 published accounts, but it is so much brighter than they would 

 lead one to suppose that it is very difficult to believe that it is 

 not changing very rapidly. The observation of one to whom the 

 ring is familiar would settle this point. A. A. Common 



Ealing, October 13 



Suicide of the Scorpion 



Doubts having been expressed at various times, even by 

 learned naturalists, as to the reality of the suicide or self-destruc- 

 tion of the scorpion by means of its own poison, and these 

 doubts having been again stated in Nature, vol. xx. p. 553, by 

 Mr. R. F. Hutchinson, of Peshawar, as the result of his own 

 observations, I think it may be useful to give an articulate ac- 

 count of the phenomenon as it has been related to me by an 

 eye-witness, which removes all possible doubt as to its occurrence 

 in certain circumstances. 



While residing many years ago dming the summer months at 

 the baths of Lucca, in Italy, in a somewhat damp locality, my 

 informant, together with the rest of the family, was much 

 annoyed by the frequent intrusion of small black scorpions into 

 the house, and their being secreted among the bedclothes, in 

 shoes, and in other articles of dress. It thus became necessary 

 to be constantly on the watch for these troublesome creatures, 

 and to take means for their removal and destruction. Having 

 been informed by the natives of the place that the scorpion 

 would destroy itself if exposed to a sadden light, my informant 

 and her friends soon became adepts in catching the scorpions 

 and disposing of them in the manner suggested. This consisted 

 in confining the animal under an inverted drinking-glass or 

 tumbler, below which a card was inserted when the capture was 

 made, and then, w aiting till dark, suddenly bringing the light of 

 a candle near to the glass in which the animal was confined. 

 No sooner was this done than the scorpion invariably showed 

 signs of great excitement, running round and round the interior 

 of the tumbler with reckless velocity for a number of times. 

 This state having lasted for a minute or more, the animal sud- 

 denly became quiet, and turning its tail or the hinder part of its 

 body over its back, brought its recurved sting down upon the 

 middle of the head, and piercing it forcibly, in a few seconds 

 l^ecame quite motionless, and, in fact, quite dead. This obser- 

 vation was repeated very frequently ; in truth, it was adopted as 

 the best plan of getting rid of the animals, and the young people 

 were in the habit of handling the scorpions with impunity imme- 

 diately after, they were so killed, and of preserving many of 

 them as curiosities. 



In this narrative the following circumstances are worthy of 

 attention: — (i) the effect of light in producing the excitement 

 amounting to despair which causes the animal to commit self- 

 destruction ; (2) the suddenness of the operation of the poison, 

 which is probably inserted by the puncture of the head into the 

 upper cerebral ganglion ; and (3) the completeness of the fatal 

 .symptoms at once induced. 



I am aware that the phenomena now described have been 

 observed by others, and they appear to have been familiarly 

 known to the inhabitants of the district in which the animals are 

 found. Sufficient confirmation of the facts is also to be found 

 in the narratives of G. Biddie and "M. L." contained in 

 Nature, vol. xi. pp. 29, 47, and it will be observed that the 

 circumstances leading the animal to self-destruction in these 

 instances were somewhat similar to those narrated by my in- 

 formant. It is aliundantly clear, therefore, that the view taken 

 by Mr. Hutchinson, viz., that the "popular idea regarding scor- 

 pionic suicide is a delusion based on an impossibility " is wholly 

 untenable ; and indeed, the recurved direction of the sting, 

 which lie refers to as creating the impossibility of the animal 

 destroying itself, actually facilitates the operation of inflicting 

 the wound. I suppose Mr. Hutchinson, arguing from the 

 analogy of bees or wasps, imagined that the sting would be lient 

 forivards upon the body, whereas the wound of the .scorpion is 

 invariably inflicted by a recurvation of the tail over the back of 

 the .animal. ALLEN TllO.visON 



Lomlon, October 11 



Climatic Effects of the Present Eccentricity 

 I ASK for an explanation of the follow ing difficulty : — 

 Dr. CroU says, in his " Climate and Time " (p. 65), that "the 



