24 Mr Harris on Magnetic Intensity, Sfc. 



either in the rate or arc of vibration, as compared with the oscil- 

 lations previously taken, when this artificial aurora was not present. 

 38. I have been led to offer these inquiries to the attention 

 of the Royal Society of Edinburgh, under an impression that 

 they contain enough of useful matter, to render them not un- 

 worthy of its consideration : on this account, alone, I venture to 

 hope, that the Society may be induced to accept them. The 

 measurement of the magnetism of the earth must be at least 

 considered a vast and most important object of physical research. 

 An attempt, therefore, to perfect the ordinary methods of obser- 

 vation, may not be altogether without its use, in the present 

 state of general science.* 



Plymouth, April 5. 1833. 



* I am much indebted to Mr Cox, maker of Philosophical apparatus at Devon- 

 port, for his valuable assistance in the construction of the Instruments described in 

 this Paper. 



