NA TURE 



;6i 



THURSDAY, AUGUST 17, 1893. 



OLD AND NEW ASTRONOMY. 

 Old and New Astronomy. By Richard A. Proctor, 

 completed by A. Cowper Ranyard. (London: Long- 

 mans, Green and Co., 1892.) 

 AS originally designed by Mr. Proctor, this work was 

 to contain a complete account of the Old and New 

 Astronomy, particular attention being paid to the latter 

 portion, which he wished to make a special feature of 

 the book. It was to be issued in twelve monthly parts, 

 the first of which duly appeared in March 1888; but 

 unfortunately Mr. Proctor did not live to complete what 

 he intended to be his mngnuin opus, and at the time of 

 his death in September 1888 only seven parts were in 

 type and the manuscript of the chapters on the planets 

 well advanced. Although a considerable propor- 

 tion of the materials for the chapters on the new 

 astronomy had been collected, nothing had been written 

 for that portion of the book. Mr. Ranyard undertook 

 to complete the work, and as we now have it five-sixths 

 of the book deals with the ancient and old astronomy, 

 and is due to Mr. Proctor ; while the remaining portion 

 by Mr. Ranyard deals with some of the work and problems 

 of the new astronomy. Unfortunately the book had grown 

 to such an enormous size that promised chapters on 

 meteors and comets were omitted and we have the 

 strange anomaly of a work on astronomy in which 

 neither of these important phenomena are dealt with. 



It is to be regretted that Mr. Ranyard, in finishing the 

 book, did not attempt to draw up a list of the errata 

 which "must inevitably occur in a work of this kind," 

 and that he did not see fit to add in some places details 

 of important points, the original omission of which was 

 probably accidental. For instance, in the first chapter 

 which gives an account of ancient and modern methods 

 of observing the heavenly bodies, we find it indicated 

 that the reflecting telescope suffers from chromatic 

 aberration (page 45) ; and although stress is laid on the 

 " amazingly exact system of modern measurement" the 

 two essential instruments, the filar micrometer and 

 the chronograph, are not even mentioned. Later on, in 

 dealing with spectroscopy, the diffraction grating is not 

 dealt with, and there is no mention of the grating spectro- 

 scope. We venture to think that no work on astronomy 

 can be considered complete in which such essentials to 

 the proper comprehension of the subject are omitted. 



In the chapters on the shape of the earth, the apparent 

 motions of the sun, moon, and planets, the true mechanism 

 of the solar system, and the measuring and weighing 

 of the solar system, we find Mr. Proctor probably at his 

 best, the subjects being treated in considerable detail, 

 although there is very little that has not already appeared 

 in his earlier works. 



Two chapters are devoted to the sun and its surround- 

 ings, and here Mr. Proctor differs from most of the 

 authorities on the subject. He assumes that the forma- 

 tion of a spot is usually preceded by the formation of a 

 facula, although the subject is still under discussion and 

 the weight of evidence at present is distinctly in favour 

 of the opposite conclusion. Now that Prof. Hale has 

 MO. 1242, VOL. 48] 



enabled us to supplement our photographic study of sun- 

 spots by photographs of all the faculae on the solar disc, 

 we may shortly hope to be able to fully trace the life his- 

 tory of solar disturbances in particular regions of the sun, 

 and so to obtain a firm basis for a definite conclusion in 

 the matter. We are also told in this chapter that we are 

 forced to the conclusion that sun-spots are produced in 

 the main by uprushes of intensely heated vapours from 

 below the photosphere, but the generally accepted view 

 is that spots are due to downrushes of comparatively cool 

 matter from the regions above the photosphere. The 

 main objection to the view that sun-spots are due to up- 

 rushes of intensely heated matter is that the bright lines 

 in sun-spot spectra are few, and are not those usually as- 

 sociated with extremely high temperature. 



The interesting chapter on the sun's surroundings is 

 marred by personalities which render it practically 

 impossible to consider this portion of the book as dis- 

 passionate scientific work. We may mention, however 

 one error of fact which Mr. Ranyard should have cor- 

 rected. On page 408 we are told that the eclipse of i860 

 is remarkable as the first in which photography was em- 

 ployed to secure views of the corona, whereas Majocchi, 

 at Milan, in 1842, had unsuccessfully tried this method 

 of observation ; and Berkowski, July 28, 1851, had 

 obtained a perfectly successful picture showing the 

 prominences and corona. 



The chapters on the planets are, as might have been 

 expected, very full and complete, but contain little that is 

 new or calls for special comment. The method of illus- 

 trating the seasons on the earth by a series of diagrams, 

 showing our planet as seen from the sun at 6 a.m., mid- 

 day, 6 p.m., and midnight at Greenwich, on one day in 

 each month, may, however, be noticed as certainly an 

 advance on the very unsatisfactory method usually found 

 in works on astronomy. It is also interesting to note 

 that the moon is properly considered as a planet. 



In the discussion of the temperature of the lunar 

 surface, we are told that merely theoretical considera- 

 tions could be thoroughly relied upon as proving that the 

 temperature during the lunar day exceeds that of boiling 

 water ; and Lord Rosse's measurements which indicate a 

 temperature of fully 500° Fahrenheit, are accepted, 

 while those of Prof. Langley, which assign a tempera- 

 ture below freezing point, are rejected as being affected 

 by some unknown cause of error. Later researches 

 by Mr. Boys have, however, confirmed Prof. Langley's 

 results, and it would have been an advantage had Mr. 

 Ranyard noted this in the completed volume. 



In the chapters on stars and the new astronomy Mr. 

 Ranyard gives in the beginning a full account of parallax, 

 and presents an interesting diagram showing the dis- 

 tances of all stars whose parallaxes have been determined 

 during the present century. The theories of the earlier 

 astronomers with regard to the construction of the stellar 

 universe are passed in rapid review, due credit being 

 awarded to the work of Thomas Wright, of Durham, 

 who really anticipated many of the speculations of Sir 

 William Herschel. The various later disc, ring, and 

 spiral theories of the Milky Way are carefully discussed 

 and compared with the latest researches of Prof. E. C. 

 Pickering and Dr. Gould, the whole object of the work 

 being obviously to give a full and fair statement of fact, 



