 Using the measurements from the Toronto and Hobart sites , Sabine noticed both short @-@ term fluctuations in magnetic declination over a period of hours , and longer @-@ term variations over months . He quickly concluded that the short term variations were due to the day / night cycle , while the longer term ones were due to the number of visible sunspots . He published two introductory papers on the topic in the Philosophical Transactions of the Royal Society . The first , in 1851 , was a collection of early measurements ; the second in 1852 correlated with Heinrich Schwabe 's sunspot measurements , which had been made widely available in Alexander von Humboldt 's Cosmos , also published in 1851 . With further data collected from the Toronto site , Sabine was able to demonstrate conclusively that the eleven @-@ year sunspot cycle caused a similarly periodic variation in the Earth 's magnetic field . He presented a third and conclusive paper on the topic in 1856 , " On Periodical Laws Discoverable in the Mean Effects of the Larger Magnetic Disturbances " , in which he singled out the Toronto site for particular praise . 
 Using the measurements from the Toronto and Hobart sites , Sabine noticed both short @-@ term fluctuations in magnetic declination over a period of hours , and longer @-@ term variations over months . He quickly concluded that the short term variations <a href='uninflect' title='1'><mark>were</mark></a> due to the day / night cycle , while the longer term ones <a href='uninflect' title='2'><mark>were</mark></a> due to the number of visible sunspots . He published two introductory papers on the topic in the Philosophical Transactions of the Royal Society . The first , in 1851 , was a collection of early measurements ; the second in 1852 correlated with Heinrich Schwabe <a href='null_genetive' title='3'><mark>'s</mark></a>sunspot measurements , which <a href='been_done' title='4'><mark>had</mark></a> been made widely available in Alexander von Humboldt <a href='null_genetive' title='5'><mark>'s</mark></a>Cosmos , also published in 1851 . With further data collected from the Toronto site , Sabine was able to demonstrate conclusively that the eleven @-@ year sunspot cycle caused a similarly periodic variation in the Earth <a href='null_genetive' title='6'><mark>'s</mark></a>magnetic field . He presented a third and conclusive paper on the topic in 1856 , " On Periodical Laws Discoverable in the Mean Effects of the Larger Magnetic Disturbances " , in which he singled out the Toronto site for particular praise . 
Using the measurements from the Toronto and Hobart sites , Sabine noticed both short @-@ term fluctuations in magnetic declination ova a period of hours , and longer @-@ term variations oovamonths . He quickly concluded that the short term variations was due to da day / night cycle , while tdalonger term ones was due to the number of visible sunspots . He published two introductory papers on the topic in thdahilosophical Transactions of the Royal Society . Thedarst , in 1851 , was a collection of early measurements ; the second in 1852 correlated with Heinrich Schwabe  sunspot measurements , which done been made widely available in Alexander von Humboldt  Cosmos , also published in 1851 . With further data collected from the daonto site , Sabine was able to demonstrate conclusively that the edaen @-@ year sunspot cycle caused a similarly periodic variation in the Eada  magnetic field . He presented a third and conclusive paper on the topdain 1856 , " On Periodical Laws Discoverable in the Meandafects of the Largedaagnetic Disturbances " , in which he singled out the Torontdaite for particular praise .