«r 



233 



Auroral waves or flashes, when rising to the magnetic pole, cause 

 a violent agitation of the needle, which consists of an irregular oscil- 

 lation, sometimes to the amount of nearly a degree, on each side of 

 its mean position. When the aurora ceases, the needle soon returns 

 to its former state. 



An auroral arch has little, if any, influence on the magnetic 



needle. 



During snow storms and thunder storms, I have commonly ob- 

 served considerable agitation of the needle, like that arising from a 

 shaking of the whole building, but have never seen any deflection 

 of the needle. No great weight, however, can be attached to this 

 observation, for it is by no means uncommon for the needle to shake 

 with a very tremulous motion, even when there is no agitation of the 

 building, and no perceptible cause for the disturbance. 



Art. III. — On the Transition Rocks of the Cataraqui; by Capt. 



R. H. Bonnycastle, R. En. 



agrams 



Continued from Vol. xxiv, page 104 of this Journal. 



\ 



Having described as well as I was able, the singular horizontal 

 basaltiform or prismatic limestone of Kingston, I now request the 

 reader's attention to the accompanying lithograph, as although it is 

 very rudely executed, it is interesting from its having been drawn 

 on a new species of lithographic stone, which contrary to all others 

 hitherto used, is nearly black and resembles marble, when smooth- 

 ed for the printer's use. 



It is however, highly adapted to the art, particularly in c 

 and maps, and not so subject to fracture under pressure. 



These drawings represent the basaltiform lithographic limestone 

 of Kingston, as viewed at two points, near the western end of the 



town. 



The upper one, shews the beds, as they appear from the edge of 

 the water forming the bank; the under one, the beds viewed at their 

 extremities, left open by quarrying, and in this view the octagonal 



figure is completely displayed. 



The third view heretofore mentioned, was a bird's eye one, and 

 shewed the basaltiform beds extending into the lake, but to what 

 distance I have not however, been able to ascertain. This drawing 



Vol. XXX— No 



30 



