4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 95 



Taking the above facts into consideration along with the known dis- 

 turbing influence of Venus, it seems, if not hopeless, yet very difficult 

 to detect with certainty any effects of the relative positions of Mer- 

 cury and the Earth upon the visible spottedness of the Sun. 



Nevertheless, the sun-spottedness of 20 periods of 116 days each, 

 starting from the inferior conjunction of Mercury and the Sun, were 

 added and their mean sun-spot numbers were represented graphically. 

 The resulting curve was very irregular and gave no plain indication of 

 a marked sun-spot activity at either conjunction. However, in the 

 twenty ii6-day periods the sun-spot numbers at inferior conjunction 

 averaged 48, and on the 58th day after inferior conjunction they 

 averaged 57, showing an increase of about 15 percent when the Earth 

 and Mercury were on opposite sides of the Sun. 



It seems unwise to lay too much stress upon this one set of observa- 

 tions. A very large number of such series taken at widely distributed 

 intervals would be necessary to determine with certainty the influence 

 upon visible sun spots of the relative positions of Mercury and Earth. 



An attempt was made to determine whether there is an appreciable 

 difference in sun-spottedness as seen from the Earth when Venus and 

 Mercury are on the same, or on opposite, sides of the Sun. TAventy- 

 two groups of 5 days each were taken when Venus and Mercury were 

 at the same heliocentric longitude, and the mean value of the sun- 

 spot numbers for the no days so taken was 35.4. 



Twenty-three groups of 5 days each, covering the same period 

 taken when the heliocentric longitudes of Venus and Mercury differed 

 by 180 degrees, gave a mean value for the sun-spot numbers of 44.2 

 for the 115 days. 



Forty-four groups of 5 days each, covering the same period, were 

 taken when the heliocentric longitudes of the planets differed by 90 

 degrees. The mean value of the sun-spot numbers for these 220 days 

 was 38.5. 



The mean value of the observed sun-spot numbers when the planets 

 were on opposite sides of the Sun was 24.9 percent greater than when 

 they were on the same side. The observed spottedness when the 

 planets were at an angular separation of 90 degrees was 8.8 percent 

 greater than when they were on the same side of the Sun and 12.9 

 percent less than when they were on opposite sides of the Sun. 



The above data do not take into consideration the relation of either 

 planet to the Earth during the period under consideration, and it seems 

 probable that a similar set of data taken at a different time would show 

 dift'erent results. Nevertheless, they seem significant and are given for 

 whatever they are worth. 



