endowments, and the story of his life faithfully told would have all the charm of a noble romance.C. C. Bonnet.
"Chicago, February 17, 1877."
THE SUN-SPOT PERIODS.
To the Editor of the Popular Science Monthly.
In the course of an inquiry 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 written 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 intermediate between, the maxima of the sunspots.
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, almost exactly intermediate between the maximum 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 fact which 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 identical 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 different specific gravity, and which do not readily mix, be poured into the same caldron, the lighter will rise to and cover the surface. If the one of the least specific gravity 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 alternately, the reflection will be alternately greater or less, according as each liquid predominates at the surface.
Suppose that, instead of other agitation, heat be applied to the bottom of the caldron. 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 sun is enveloped in, and covered by, an exceedingly 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 phenomenon of sun-spots.
Now, is it not logical to infer that the increased action which ruptures the photosphere 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. W. Chapman.
A PRETTY BIG DOG-STORY.
To the Editor of the Popular Science Monthly.
The perusal of the interesting article on "Canine Sagacity," which appeared in the December number of The Popular Science Monthly, gave me great pleasure, and caused me to recall to memory a very remarkable case of the same character 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 me 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 movements 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 uneasy 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 astonishing. 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 running for the doctor. This dog, who was only eight months old, had never received any kind of training. 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
