Extra Observations of Magnetometers, March 29 — April 7. 1843. 61 



NOTES ON THE AURORA BOREALIS. 



d. h. m. 

 larch 29 An Auroral light was seen about 9^ to NNW., assuming the form of a segment of a cii-cle, which 



became rather bright about 9'^ 50™, the light being homogeneous ; at 10'' 50™ the light was 

 more spotted, but no pencils were visible. At 10^ 25™ a meteoric light was seen, at first 

 rather faint, proceeding from a point 1° to the south of Zeta Orionis (which was then just seen 

 to about WSW. above the surrounding trees), passing between Castor and Pollux, and lost in a 

 nebula in the back of Leo Minor. It became gradually brighter till about lO'' 35™, when its 

 brightness perhaps equalled the most vivid pencils of an aurora, and gradually diminished in 

 intensity and length till altogether lost about lO"^ 55™. The breadth at Orion was about I'', 

 this being the brightest portion of the meteor, but increasing gradually upwards, fillino- the 

 space between Castor and Pollux ; the greatest length seen might be about 100.° There was 

 no appearance of corruscations. This meteor, undoubtedly connected with the aurora, was 

 singular in every way, whether we regard its form, position, isolation, or duration. 

 The Aurora had disappeared at 12^. 



pril 5 9 30. Aurora, altitude about 35° or 40° ; streamers and corruscations, brightest to N. by E. 



9 40. Bright auroral arch stretches from W. to NE., altitude 30°, sending streamers downwards to N. 



10 15. Splendid aurora, originally with a double arch, the greatest having an altitude of 80°, the other of 

 60°, spanning 150° of horizon. An auroral pencil seen frequently in the same position as 

 that observed on March 29, but never having the same duration. The aurora is brightest 

 to NE. by E., the E. extremity of the arch, although the moon being near that point renders 

 it less obvious. A portion to the E., which is brightest, branches off in a cycloidal form. The 

 arch is sometimes triple, the lowest being 10° altitude, with pencils of aurora between. 



10 20. Arches more broken, and sending pencils up to the zenith. Arches broken into pencils, vivid 

 from W., and directed a little to the S. of the zenith. 



10 22. Arch altogether irregular to E. as if broken into small arches, with a bright mass to NNW. and 

 NW., extending to the W. extremity of the arch, but broken at the IST. ; the dai-k space below 

 having pencils occasionally. 



10 25. Pencils to W., very bright ; arch strangely irregular, the light space being about 15° broad, and 

 generally cycloidal at the terminations on the horizon. A long pencil seen frequently to W., 

 as at 15™. 



11 11. The arch now spans 130° of horizon, is 30° altitude, and 5° broad, with broad brushes of light 

 below ; the western extremity of the arch is bent inwards towards the north. 



11 34. Arch only 10° altitude. 



12 30. Arch spans 130°, 12° altitude, 6° or 7° broad, and the form is cycloidal : no pencils at present. 



12 45. Again double arches, but close to each other; occasionally pencils from the NE. extremity. The 

 moon is below the arch to WNW., and has a corona the breadth of its own diameter ; the sky 

 is beautifully clear, the stars appearing very brilliant, and no clouds are to be seen. 



13 0-5. Strong pencils from the E. extremity of the arch. A new arch commencing at NNW., is spring- 

 inof up with the other ; its altitude is 8°. The apex of the greater arch is about N. 5° W., and 

 the breadth is increasing from 3° to 10° — much flickering. 



14 0. Auroral arch much broken — altogether diminished ; patch of cloud to NNW. 



)ril 5 15 30. The sky became quickly covered with scud — the aurora gone. 



)ril 7 14 0. An aurora to N., in the form of portion of an arch, 10° broad, reaching from W. to NNW. — 

 Jlickering, but no pencils. 



16 0. Faint auroral mass of light, 8° high and broad, variable in brightness, flickering. 



16 35. Auroral light still flickering to NNW. — strong twilight. 



MAG. ANT) MET. OBS. 1843. 



