488 



THE POPULAR SCIENCE MONTHLY. 



endowments, and the story of his life faith- 

 fully told would have all the charm of a 

 noble romance. C. C. Bonnet. 



"Chicago, February 17, 167T." 



THE SUN-SPOT PERIODS. 



To the Editor of the Popular Science Monthly. 



In the course of an hiquiry lately made 

 in reference to the periodicity of cold 

 seasons, and their coincidence with the 

 greatest prevalence of the sun-spots, I came 

 to the conclusion (the reverse of that reached 

 by most of those who have wii!.ten on that 

 subject) that, while there is a recognized 

 periodicity in the sun-spot maxima, and also 

 a seeming periodicity in the recurrence of 

 cold seasons, the cold winters, instead of 

 falling coincident with, oftenest occur inter- 

 mediate between, the maxima of the sun- 

 spots. 



I think the coldest season of the present 

 century was that of 1816, while the sun-spot 

 maximum for that period is placed in 1817. 

 Another remarkably cold winter, and one 

 of which I have a vivid recollection, was 

 that of 1856 ; while the nearest sun-spot 

 maxima were in 1849 and 1860. Another 

 unusually cold winter occurred in 1866, al- 

 most exactly intermediate between the maxi- 

 mum of 1860 and that which followed. 



It seems to be taken for granted that 

 the sun emits less heat during the time it is 

 partially covered with spots. But is this a 

 ftict Avhich is substantiated by experiment ? 

 It is easy to see that its light may be less ; 

 but light and heat, though originating and 

 being propagated similarly, are not identi- 

 cal either in their effects or in the mode of 

 propagation. Thin wave-undulations differ 

 very greatly in length and frequency. 



If two liquids of different colors and dif- 

 ferent specific gravity, and which do not 

 readily mix, be poured into the same caldron, 

 the lighter will rise to and cover the sur- 

 face. If the one of the least specific grav- 

 ity be the lightest in color, it will reflect 

 light the most readily ; and, if the contents 

 of the caldron be agitated, so that the two 

 liquids be made to show at the surface al- 

 ternately, the reflection will be alternately 

 greater or less, according as each liquid 

 predommates at the surface. 



Suppose that, instead of other agitation, 

 heat be applied to the bottom of the cal- 

 dron. Gradually, with the increase of the 

 heat, upward jets are produced, and the 

 darker liquid breaks through the lighter 

 surface in the act called boiling. These 

 dark fractures of the light surface do they 

 not correspond to the sun-spots ? 



In its ordinary state, the body of the 

 snn is enveloped in, and covered by, an ex- 

 ceedingly bright surface, appearing to be 



slightly reticulated, called the photosphere. 

 When this photosphere is undisturbed, we 

 have the maximum of light. At other times, 

 apparently by increased internal action, the 

 uniformity of this photosphere is destroyed ; 

 titanic forces, acting from beneath, rupture 

 it, and produce what to us is the phenome- 

 non of sun-spots. 



Now, is it not logical to infer that the 

 increased action which ruptures the photo- 

 sphere is accompanied by increased heat- 

 radiation ? If it be, there is reason for the 

 cold seasons falling not coincident with, but 

 intermediate between, the sun-spot maxima. 

 Geo. AV. Chapman. 



A PEETTT BIG DOG-STOPvY. 



To the Editor of the Popvlar Science Monthly. 



The perusal of the interesting article on 

 " Canine Sagacity," which appeared in the 

 December number of The Popclar Science 

 Monthly, gave me great pleasure, and caused 

 me to recall to memory a very remarkable 

 case of the same chai-acter which came under 

 my own observation about two years ago. I 

 was then practising medicine in Galveston, 

 Texas. One day I was called to see a patient, 

 Mrs.Wechsler, the wife of a German butcher. 

 As I entered the hall of the house where 

 she lived, I was met by a large black dog, 

 who under no consideration would let ne 

 pass, until Mr. Wechsler himself came to 

 pacify him and assure him that it was all 

 right. The dog then followed us into the 

 sick-room, and, while I was examining the 

 patient, the dog was watching all my move- 

 meiits most attentively. When I departed, 

 I noticed that I was followed by the dog, 

 who did not leave me until he had seen me 

 enter my office. A few days after this the 

 dog entered my office apparently very un- 

 easy about something. The thought struck 

 me at once that perhaps I might be wanted ; 

 so I put on my hat and followed the dog, 

 who immediately started for home, where I 

 found Mrs. Wechsler sick in bed, with no 

 one in the house to attend to her. She was 

 surprised at my timely call, and, when I 

 told her that I had been called by the dog, 

 she related to me what was even more as- 

 tonishing. She had suddenly been seized 

 by a violent attack of vomiting fifteen or 

 twenty minutes previously, when the dog 

 had picked up an empty tin pan and placed 

 it beside her bed, before rnnning for the 

 doctor. This dog, who was only eight months 

 old, had never received any kind of tiain- 

 ing. It is therefore evident that something 

 like the following train of thoughts must 

 have passed through his mind : Seeing me 

 examine the patient and prescribe for her, 

 he must have conceived the idea that I was 

 the proper person to be there when she was 

 sick. Having made up his mind on this 



