158 Literary Notices. 



Ph.D., F.R.S., F.R.A.S. ; Balfour Stewart, Esq., M.A., F.R.S. t 

 Superintendent of the Kew Observatory, and Benjamin Loewy, 

 Esq., Observer and Computer of the Kew Observatory. Second 

 Series (in continuation of First Series). Area and Measurements- 

 op the Sun Spots, observed by Carrington during the seven years 

 from 1854 to 1860 inclusive, and deductions therefrom. (Taylor and 

 Francis.) — To verify the observations of Carrington by comparing 

 them where practicable with the Kew photograph was one part of 

 the labours which are recorded in the " Second Series" of the 

 Researches on Solar Physics, and then to ascertain what indications 

 they afforded of the laws regulating the appearance and distribution 

 of spots. The authors have constructed an elaborate table showing 

 the proportion which the spotted area bore to the solar surface for 

 each day on which an observation could be made between 1854 and 

 1860 inclusive. Another inquiry related to the distribution of spots 

 on the disc of the sun, and from this it appears that the " average 

 size of a spot varies with the ecliptical longitude, and there is a 

 periodical recurrence in their behaviour, and the period of recur- 

 rence of the same behaviour appears to be nineteen or twenty 

 months." " In all these recurrences the progress of the maximum 

 is from left to right, not from right to left." " The period of 

 twenty months," say the writers, will enable us to determine which 

 of the inferior planets exercises the predominant influence on sun 

 spots. We have to ask which of the two inferior planets takes 

 twenty months to return to the same position with respect to the 

 earth. This evidently points to Venus, for which the synodical 

 period is 583 days, or between nineteen and twenty months." 

 Jupiter appears also to affect the spots, and when both that planet 

 and Venus are in opposition to the earth, large spots appear, and the 

 average seems smaller when Venus is in opposition and Jupiter in 

 conjunction. With reference to the position of the spots, " it would 

 appear that spots are nearest to the solar equator when the helio- 

 graphical latitude of Venus is 0°, and are most distant from the 

 solar equator when the planet attains its greatest heliographical 

 latitude." 



The writers remark, " it is not to be inferred that the mechanical 

 equivalent of the energy exhibited in sun spots is derived from the in- 

 fluencing planet, any more than it is to be inferred that the energy of a 

 cannon ball is derived from the force with which the trigger is pulled.. 

 The molecular state of the sun, just as that of the cannon or of ful- 

 minating powder may be extremely sensitive to impressions from 

 without. We may infer from certain experiments, especially those 

 of Cagniard de Latour that at a very high temperature, and under 

 a very great pressure, the latent heat of vaporization is very small, 

 so that a comparatively small increment of heat will cause a con- 

 siderable mass of liquid to assume the gaseous form, and vice versa." 

 From t lie preceding remarks and extracts it will be seen that the 

 Second Series of Solar Physics is of high value. Is not their title 

 awkward? "Researches on Solar Physics." We search into a 

 matter. A search or research on the earth would be a search 

 conducted upon it, not necessarily one into its elements or com- 

 position. 



