1886.] Sim-spot Areas and Diurnal Declination-ranges. 221 



a few of the most disturbed observations, embracing those which 

 denote ranges above forty scale-divisions, or 28''8. Although this 

 rejection has been made, it must not be supposed that the remainder 

 are entirely undisturbed, but only that they are freed from the 

 excessive influence of the most violent disturbances. 



We have extracted the Prague ranges from the published records of 

 that Observatory, and we have not found it necessary to exclude dis- 

 turbances except in one or two very marked cases. The Prague 

 ranges are derived from observations made at 6 a.m., 10 a.m., 2 p.m., 

 and 10 p.m., hours which are common to the whole series, and there 

 is reason to believe that the ranges thus deduced are not greatly 

 different from those which would have been obtained from an hourly 

 series of observations. 



2. The declination-ranges of the present paper have been reduced* 

 exactly in the same manner as the temperature-ranges of our previous 

 report (" Proc. Roy. Soc," May 1, 1884, vol. 37, p. 290). It is there: 

 fore unnecessary to discuss the method of reduction, this having been 

 already done at considerable length. 



We proceed consequently at once to consider — 



Results of Comparison around 24 Days. 



3. Comparison as to Duration of Period. — This is given in the fol- 

 lowing table, in which the sun-spot and Toronto temperature columns 

 are transcribed from our former paper for the purpose of comparison. 

 The sums in these columns are those of 36 years. The Prague decli- 

 nation columns exhibit likewise sums of 36 years, while the Toronto 

 declination columns exhibit sums of 24 years. As in our last paper, 

 to save space we have divided each individual sum by 100 ; that is to 

 say, we have dismissed the two right hand figures. 



We have inclosed in brackets the positions of all sufficiently well- 

 defined maximum Inequalities of sun-spots, of Toronto temperature- 

 ranges, and of Prague declination-ranges. But inasmuch as the 

 Toronto declination-ranges only extend over 24 years, we have 

 merely exhibited the numbers without brackets, believing these to be 

 of inferior accuracy. 



Before the table is examined it may be well for the reader to be 

 reminded that the sun-spot areas extend from 1832 to 1867 inclusive, 

 thus embracing 36 years ; that the Toronto temperature and the 

 Prague declination-ranges extend from 1844 to 1879 inclusive, thus 

 embracing 36 years ; while the Toronto declination-ranges extend 

 from 1856 to 1879 inclusive, thus embracing 24 years. It thus 

 appears that the Toronto temperature and the Prague declination- 

 raDges are for the same 36 years, 24 of which they have in common 

 with the sun-spot series. On the other hand, the Toronto declination 



