Cy9 



Tlie mean horizontal force for each month is nearly the same as 

 the mean for midnight and for 1'' p.m. 



The secular variation is positive, the increase being considerably 

 less for 1845, than for any of the previous years. 



When the annual variation is eliminated from the means for each 

 month, tlie author finds that the secular variation is scarcely sensible 

 about 6*' 40'" a.m., an hour after the morning maximum, in the 

 first six months of the year 1844, and about 4'> 40™ p.m., an hour be- 

 fore the afternoon maximum, in the last six months of the same year. 

 A lunar period for the horizontal force has been deduced, which 

 (like the annual period, and the sun's declination) shews maxima 

 when the moon has its greatest N. and S. declination, and minima 

 between these periods. Each of the years 1844 and 1846 give 

 nearly the same result. 



The author has also deduced a period depending on the moon's 

 phase or synodical revolution, consisting of a maximum of horizonUl 

 intensity, about two or three days after the new moon, and a mini- 

 mum about two or three days after the full moon : this period is 

 shewn with the same distinctness and regularity in each of seven 

 months of 1844. 



The Observations for 1844 and 1845 have each been investigated 

 for the determination of a period connected with the moon's hour 

 angle ; the author finds this period to consist of two maxima and two 

 minima. From the Observations for 1844, (Ac minimum occurs about 

 5 hours before the moon's meridian passage, the maximum about 

 IJ hours after the passage of the inferior meridian; a maximum oc- 

 curs before 4'' after the meridian passage, and a minimum about 

 8 hours after the meridian passage. These periods have been veri- 

 fied by the Observations for 1845, excepting that, for 1845, the se- 

 condary maximum occurs before 3 hours after the meridian passage : 

 the range for each year is nearly the same, being about a tenth part 

 of the mean diurnal range for the year. 



3. Experiments and Investigations as to the influence 

 exerted over some Minerals by Animal and Vegetable 

 matter, under certain conditions. By Mrs Margaret 

 Henrietta Marshall. Communicated by Sir T. M. Bris- 

 bane, Bart. 



It occurred to the author, while examining the fossils of various 



