72 . Litelligence atid Miscellaneous Articles. 



with many streamers ; the height of this arch, estimated by /3 Dra- 

 eonis, was about 8°. Again, at 7^^ 45", there was a brilliant display 

 of sti-eamers, and an arch which was about 12° in altitude. There 

 was also at the height of 3° or 4° a long sinuous line of white light. 

 A day or two afterwards I was in Northamptonshire, not far from 

 Banbury, and found that on the night in question the arches had 

 been noticed at considerable altitudes : my observation then became 

 of use ; for having a base line of as nearly as possible twenty miles, 

 and the small angle accurately taken, the angle at the other end being 

 large, a considerable inaccuracy in this angle will not greatly affect 

 the result. If we take the crown of the arch to have been in the 

 zenith of this station at 7^ 45™ p.m., as I was informed at that time 

 it was about over head, and could not be seen without going out of 

 doors, we shall find the height of the crown of the arch to have been 

 41 miles, or about 22,400 feet. From a rough estimate of the space 

 which the arch subtejided in azimuth, the distance between its feet 

 was twelve or fourteen miles, which rested, as it appeared, on con- 

 fused masses of auroral light in the N.E. and N.W., which must 

 have been about the height of the ordinary cirrus. The true shape 

 of the arch therefore appears to have been a long flat curve, of which 

 the subtense was equal to six or seven times its altitude. 



It seemed also that the long sinuous line which I mentioned as 

 seen through the arch was formed of a number of these arches at a 

 much greater distance, the direction of which was not in a straight 

 line, though possibly parallel to one another. 



From frequent observation, I believe that the streamers which 

 usually attend the display of Aurora are parallel to the earth's sur- 

 face and to one another, and that their convergence is apparent only, 

 and produced by perspective. Probably also, whenever the elec- 

 tricity in this state is in sufficient quantity and of opposite kinds, 

 arches are formed, the true shape of which appears to resemble the 

 magnetic curve. The varying proximity of these electro-magnetic 

 clouds will also very well account for the disturbance of the needle. 

 I am, Gentlemen, 



Your obedient Servant, 



Rose Hill, Oxford, June 15. John Slatter. 



ON LIgUID STORAX AND BALSAM OF PERU. BY M. KOPP. 



The author states, that having in preceding memoirs studied the 

 resins of benzoin and the balsam of Tolu, there remained to complete 

 the general history of the balsams to examine the balsam of Peru 

 and storax. 



Balsam of Peru had already yielded MM. Fremy and Plantamour 

 very interesting results. M. Fremy had determined the presence of 

 cinnamic acid, cinnamein and several resins : in some species of 

 balsam of Peru he met with a solid crystalline matter, to which he 

 gave the name of metacinnamein. According to this chemist, when 

 cinnamein is submitted to the action of potash dissolved in alcohol, 

 it is converted into cinnamic acid, and peruven, which is a liquid 

 body. 



