30 



KNOWLI.DGK 



January, 191J 



;nilhor has siicoci'ilfd in prudiiciiiK a work thai iiitercstH 

 "thiTS bi'sidrs himself. 



The book iiiuItT t'ciiisidcratioti is written in iion-niathciiiatical 

 kiiiKiiaKf. Tlu- fcalnro of it is the singularly small amount of 

 Icchiiiial formulae that a skilled author needs in describing 

 pleasantly and interestingly such a highly scientific and 

 complex subji-ct as the Tides. It recpiires a master-mind In 

 render the subject easily intelligible to commnn folk .ind at 

 the same time to preserve its standard so hii;li that no 

 seientilic library can be elVicient without possessing a copy 

 as a text-book or book of reference. The book has now 

 become indispensable to the astronomer and the observatories, 

 to the Kcodesist and Keographer: in short, to .ill who wish to 

 know up-to-date facts of the cosmos, particularly of those 

 important specks in the universe — the earth and moon. 



'1 here was good reason for a new edition of this work, and 

 it is expressed in the author's own words, " Kven in so short 

 a period of time as fixe years Ihc author had written the 

 mamiscript for the first edition in l.S')7. tliouiih nol piiblislicd 

 until October. KS9.Sj the aspect of some parts of niy subject 

 had already changed considerably, so that in ly02 some 

 alterations had become necessary, and now, after a further 

 lapse of eight years, yet more extensive revision is needed. 

 It is scarcely possible to revise an old book so as to make it 

 into a new one. and it is not. perhaps, desirable to attempt to 

 do so. because there is a certain interest in observing the 

 gradual devi'lopment of scientific thought. It seemed to me, 

 therefore, that the best way of incorporating into this volmne 

 the recent advances of science was to add supplements to the 

 several chapters, and only to make minor alterations in the 

 original text." 



The chapters — the tidal theory perv.iding them — which are 

 of more gener.il astronomical interest, or those beyond the 

 regions of our earth and its satelliti-, arc those on Saturn's 

 Kings (Ch.ipter .Will, originally Chapter X.\ in the first 

 edition), I'igures of Equilibrium of a rotating mass of Liquid 

 (Chapter .XI.Xl. Speculations as to the (Origin of Double- Stars 

 iCh.ipter XXi. and the Kvolntion of Celestial Sy.steins 

 (Chapter XXI I. the last three chapters being newer re- 

 written. 



We notice an error in the chapter on Saturn's Kings at the 

 foot of page .i.id. The discovery of the inner dark, or crcps, 

 ring is credited to Bond and Dawes, as having been made in 

 1850; though these two eminent observers undoubtedly saw 

 that ring independently for the first time, the credit of placing 

 the discovery definitely on record should have been given to 

 Dr. J. (j. G.ille, who had made a series of observations of this 

 dark ring in 1838. These were published a few months later. 



Not the least valuable portions are the numerous references 

 to the works of those upon which the book is based, and the 

 index — the part of a book often scamped. A few other later 

 references might have been added with advantage to some of 

 the chapters. 



The first edition had three hundred and thirty-four pages of 

 text in twenty chapters, and eight pages for the index, with 

 forty-three illustrations ; the third edition is expanded to four 

 hundred and twenty-six pages in twenty-one chapters, and 

 ten-and-a-half pages of index, with forty-eight illustrations. 

 Besides the three editions published in England, two have 

 been published in U.S.A.. two in Germany, one in Hungary, 

 and one in Italy. Altogether, a practical book of great interest, 

 well arranged and printed, and at a moderate cost. 



SOLA 



)IS irkllAN'CES DURING X()\i: M I'.i: R, 



P>\ 



i"K\NK c. i)i:xni:tt. 



'I HI-; Sun has shown more activity so far as spots «<re 

 concerned, but there has been a marked decrease in the 

 amount of faculic disturbance. Of the twenty-eight days on 

 which observations were possible the disc presented an 

 apparently clear unruffled surface (m nine, namelv the 7th. 

 Hth. nth. I4th. and 16th until 20th. whilst only a little f.iculic 

 disturbance was visible on the 5th and 6th nearing the 

 western limb. The longitude of the central meridian at noon 

 on November 1st was 240° 48'. 



No. JS. — This group, consisting of one small spot as leader, 

 possessing three umbrae, and followed by eight pores, broke 

 out suddenly on November 1st. Its length was J8,000 miles. 

 On the 2nd only the spot was seen at the western end of a 

 coarsely granulated area ; it dwindled on the 3rd and 4th, 

 when last seen, the area being marked during the next two 

 days by the above-mentioned faculic disturbance. 



No. J<). — On the 9th and 10th the position of this little pore 

 was carefully measured. On the 11th nothing was seen, but 

 on 12th and l.!th in the same area, or verv rie.ir to i(, one and 



two tiny pores respectively were seen, but their exact positions 

 could not be determined owing to the combined difficulties of 

 minute size and rapidly travelling cloudiness. 



No. 40. — A fine spot was seen to have come round the limb 

 on the 21st. rimmed on the western side by faculae. There 

 were two umbrae, and when last seen on the 29th the inner 

 edge of the penumbra was bright edged. Its diameter was 

 14.000 miles. There was a pore a little south-east on the 24th. 



Within the eastern limb on the 28th there was a small faculic 

 disturbance. 



Not only is there a falling ofl' in activity when the Sun is 

 examined with the telescope alone, but there is a similar 

 decrease in the number of prominences and other phenomena 

 shown with the spectroscope. 



Our chart is constructed from the joint observations of 

 Messrs. John McHarg, E. E. Peacock, and F. C. Dennett. 

 The wide distribution of the observing stations at Lisburn. 

 Bath, and Hackney proves very helpful in preserving the 

 conlinuitv of the record. 



DAY OF X0\1:MI5HR. 1911. 



