312 Prof. Balfour Stewart and Mr. VV. L. Carpenter. 



SS-^ TTLgj. All sufficiently good. Use TT-30, 29, 28. 



SS-30, -29, -28, and KT -26, -25, -24, all redaced to -29. 



SS.oaTT.go. Toronto temperature-range Inequality irregular; the 

 others sufficiently good. 



SS_ U , TT_ n . All sufficiently good. Use TT-12, -11, -10; 

 SS -12, -11, -10; KT -12, -11, -10, all reduced to -11. 



SS_ 2 , TT_ 5 . Kew Inequality irregular ; the others good. 

 SS., 1B , TT +10 . Sufficiently good. Use TT +9, +10, +12; SS 

 + 14, +15, +16; KT +9, +10, +11; all reduced to +10. 



SS +25 , TT +29 . Toronto Inequality irregular, also Kew Inequality ; 

 sun-spots good. 



SS +4S , TT +42 . All sufficiently good. Use TT +41, +42, +43; 

 SS -,-41, +42, +43; KT +39, +40, +41; all reduced to + 42. 



It thus appears that, out of eight cases, the sun-spots do not depart 

 from their type in a- single instance, while Toronto temperature- 

 range Inequalities are too irregular to admit of comparison in three, 

 and Kew temperature- range Inequalities in two cases, leaving four 

 unexceptionable cases for comparison. These are exhibited in Table VI 

 and in Diagram II in a manner exactly similar to that in which the 

 24-day Inequalities were exhibited in Table III and in Diagram I. 

 Also from Table VI we may draw conclusions exactly similar to those 

 which we drew from Table III, the two tables exhibiting virtually 

 the same behaviour of the various Inequalities. 



Concluding Remarks. 



22. We would remark, in the first place, that there are two possible 

 kinds of periodicity with respect to sun-spots, and that it is not neces- 

 sary to regard the Inequalities around 24 days and those around 26 

 days as perfectly similar phenomena. To illustrate our meaning, let 

 the reader imagine that some one definite hemisphere of the sun is in 

 the habit of periodically losing its brilliancy and then becoming 

 luminous again, while, however, the other hemisphere remains con- 

 stant in its lustre. We may imagine that, in the course of time, 

 an inhabitant of the earth would view these phenomena from all 

 possible quarters and in all possible phases, the result of which would 

 be that, on an average, there would be a falling off in light corre- 

 sponding to the times of extinction, and no falling off corresponding 

 to the times of maximum lustre. We should, therefore, have what 

 might be termed a solar Inequality of the first kind. 



Next, suppose that the sun by rotation carries round this state of 

 things, and thus brings next the earth the peculiar solar meridian 

 which passes through the central point of the darkness. Sometimes 

 the earth would view this meridian at its blackest and sometimes at its 

 brightest, but, on the whole, it would present an average lustre midway 



