4.6* Difference i7i the Height of Spring Tides. 



immediately above the sun j and as the twilight withdrew, the aurora 

 increased in brightness. At 9 P.M. it showed a steady flame colour, 

 and was comprised between the N.W. and N. by E. points of the ho- 

 rizon, and about nine or ten degrees in altitude. 



At 1 1 o'clock a vertical line of light, whose bearing was N. by 

 E. ^ E. emanated from the aurora, and in a few minutes afterwards 

 other coruscations emanated from it between the N.W. and N., but 

 they often disappeared, and rose again to an altitude exceeding that 

 of £ Cassiopeiae. At a quarter before 12, seven columns of light of 

 various widths appeared at once, and continued several minutes : the 

 wind blowing fresh from the westward seemed to give them a slight 

 inclination from a perpendicular towards the East, and they did not 

 finally disappear till between one and two A.M. In the course of the 

 evening several bright meteors descended from over the aurora, and in 

 a few hours afterwards a heavy gale came on from the S.W. and con- 

 tinued nearly four days. This meteoric phsenomenon was also seen 

 in Scotland, but from the interposition of clouds it did not display any 

 vertical columns there, only faint coruscations in the horizon. What- 

 ever gaseous quality an aurora borealis may possess, whether hydro- 

 genous, electric, or magnetic, or a mixture of any of these, here it is 

 very generally, if not the cause, a prognostic of a strong gale of wind 

 from some quarter. 



ON THE DIFFERENCE IN THE HEIGHT OF SPRING TIDES. 



The first, second and third tides after the new moon on the 24th 

 of April were considerably higher in Portsmouth Harbour tlian the 

 first three tides after the new moon on the 2-lth of March ; yet the 

 new moon in March was nearer to the earth's equator than the new 

 moon in April, and of course her attraction of the water was greater 

 in the former month : the sun in March was also nearer the earth 

 than he was in April, and his attraction proportionably greater. The 

 moon's horizontal parallaxes in the Nautical Almanac at the time of 

 these new moons, are the same within one second, and the greatest 

 for the year till the last day of October j yet the difference in the height 

 of the spring tides at these times was fifteen inches greater imme- 

 diately after the last new moon. It would be difficult under these 

 nearly coinciding circumstances to account for this unusual swell of 

 the tides, without referring to, and taking into consideration the state 

 of the weather, and the position and strength of the wind which in- 

 fluenced it. In March only three-fifths of rain fell here ; and the eva- 

 poration was nearly as great as that of the present month, and the 

 weather remarkably calm. In April between three and four inches 

 of rain fell, and a S.W. gale from over the Atlantic blew strong two 

 days before and two days after the last new moon, which in connection 

 with this depth of rain, must have caused the swell and comparative 

 difference in the last spring tides on our shores. A remarkably low 

 ebbing of the tide, six feet lower than is usual at the same age of the 

 moon, occurred here the third day after the new moon in March. 



OBSEKVA- 



