254 



KNOWLEDGE 



[November 1, 1900. 



the contention being that a certain compactness of the 

 photosjahere is necessai'y for the formation of the spots, 

 and that if this condition of the photosjihere is wanting, 

 either from excess or defect of compactness, no spots 

 ■will fonn : at the poles, it is suggested, there is excess 

 of compactness. But lot me hasten to mollify your 

 correspondent by assuring him that I have no theory of 

 solar physics which I wish to prove by boiling stuff in 

 a pan, he would be a bold ma.n who would venture upon 

 such a coui'se. It is quite the " other way about," and 

 even a peaceful domestic experiment may suggest lines 

 of research, and point to conclusions to be reached by 

 very different methods.— Arthur East.] 



[It should be borne in mind that Mr. East's experi- 

 ments are practically experiments upon the behaviour 

 of convection currents under certain conditions. We 

 have every reason to believe that convection currents 

 play a primary part in the maintenance of the present 

 condition of the sun, and in causing many of the phe- 

 nomena which we obsei"ve upon it. To this extent 

 Mr. East's experiments can teach us a good deal. By 

 watching the behaviour of convection currents on a 

 small scale, at feeble temperatures, and in a simple 

 liquid, we can form a more vivid idea of the behaviour 

 of convection cuiTents on a cosmical scale, at transcen- 

 dental temperatures, and in gases in which the most 

 diverse elements are mixed or combined together in the 

 most complicated manner. The experiments are most 

 instructive when their necessary limitations are kept 

 in view, nor does it seem to me that Mr. East has for- 

 gotten these. 



I should like to add my accord with Mr. Buss's 

 assumption, " that the causes of solar evolution are to 

 be found on the sun itself." The eleven-year cycle is, 

 to my view, essentially solar in its causes ; not planetary, 

 nor meteoritic. Yet I do think there is evidence of 

 a slight modifying effect of planetary position on sun- 

 spot behaviour ; the spots do not, in my opinion, owe 

 their formation to any planetary action; but their 

 growth and decay may be affected to some degree. 



[E. Walter Maunder.] 



THE NATURE OF SUN-SPOTS. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — With reference to a long series of articles 

 published in Knowledge about different observations 

 of the sun, I wish to draw the attention of your readers 

 to a question concerning the sun which, as far as I 

 remember, has not been recently touched upon, i.e., the 

 nature of solar spots. 



This was the subject of a communication which I 

 made last year to our Russian Astronomical Society, 

 in consequence of my having made observations of sun- 

 spots for a series of years. 



The observations of the spots show us without any 

 doubt that they are excavations in f/ie Solar Photosphere, 

 produced by some yet unknown process. This is pro- 

 bably caused by and consists in enormous gas-eruptions, 

 which after having torn through the photosphere of the 

 sun rise up into the higher parts of its atmosphere and 

 become apparent to us, as protuberances, if projected 

 into the space, on the sun's border, and as facul», if 

 projected on the sun's body. 



There is certainly not the least doubt that the sun's 

 temperature is rising from its surface to its centre, and 

 that the layers below the photosphere become gradually 

 the hotter the deeper they are placed. This considera- 



tion gives us the right to suppose that the sun's deeper 



layers, which we see through the openings of the spots, 



must be much hotter than the photosphere, and as such 



their immense temperatui-e produces vibrations of the 



ether, of so great a rapidity and such minuteness of 



wave length that they are out of the range of sensibility 



of our optic nerves, and are therefore unable to affect 



our sight. The consequence of this is, that we see them 



black, because every ether-vibration of a very high 



range — such as the ultrarviolet and the Rontgen-vibra- 



tions — are quite inappreciable by our eyes. 



If this supposition be proved con-ect it will be of great 



value, and will not remain without its influence on our 



consideration of the whole universe surrounding us, 



and we shall have the right to put the question : Can 



we see all the heavenly bodies which surround us, or 



can there be some of so high temjjerature that they 



are black, because quite invisible to our eyes? 



Baron N. Kaulbars. 



Perki-Torwi, Villa Zewoshko, 5. 

 — ►.*-. — 



WIRELESS TELEGRAPHY AND HERTZIAN 

 WAVES. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — I am extremely pleased and flattered by the 

 kindly critique of my little book, furnished by your 

 reviewer in the September number of Knowledge. Pre- 

 cisely because the reviewer is so generally just I beg 

 to point out that one or two inaccuracies have found a 

 place in the critique, probably owing to hurried reading. 

 In the first place, I say at p. 1, § 2, " Electricity appears 

 to be a vibratory motion in the ultimate molecules of 

 bodies," and not " an electrically charged body consists 

 in rapid vibratoi-y motions," as stated in your review. 

 At p. 3 it is distinctly stated that " conductors offer 

 little resistance to the passage of electricity " ; but in 

 no part of the book have I stated that non-conductors 

 cannot enter into that vibratoiy motion which constitutes 

 our electrified condition : on the contrary, at p. 10 it 

 is clearly stated that the insulator lying between the 

 excited body, and the induced, is primarily put into 

 the vibratory state, hence polarised, and capable there- 

 fore of setting up a like condition in the suiTounding 

 bodies, which if conductors cannot retain this strained 

 condition, hence cannot transmit the inductive effect, 

 unless themselves insulated. S. Bottone. 



September 5th, 1900. 



HIGH-SPEED TELEGRAPHY. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — No doubt once a paper ribbon is ready the 

 high speed telegraph will woi-k, but nothing is said of 

 how a ribbon with its two rows of perforations is 

 prepai'ed. This operation must, I presume, occupy 

 enormous time, and require a large amount of work. 

 Baron N. Kaulbars (Lt.-Gen.). 



St. Petersburg. 



[The perforating of the ribbons is done by a modified 

 Wheatstone perfoi'ator, and the speed is the same as 

 the speed of Wheatstone perforating. I have seen men 

 prepare ribbons for the Wheatstone at a speed of 45 

 to 50 words per minute. If we say 25 words per minute 

 we shall get a speed easily maintained for long periods. 



One man can thus prepare 25x60 — 1500 words per 

 hour. The Pollak-Virag apparatus, described in Know- 

 ledge for September, will send more than that number 

 in one minute. So it would require over 60 men to 



