330 Mr. Barlow’s observations and experiments on the 
from the room in which the experiments had hitherto been 
made, into a bower in my garden, and having detected a 
remarkable difference in the results obtained in these two 
situations, I determined to commence the experiments de novo 
in this latter spot, which was at least thirty yards distant 
from any building ; and afterwards to examine the cause of 
the difference in question. This examination is reported in 
the conclusion of this article. 
All the following experiments, therefore, will be under- 
stood to have been made in the open air, proper precautions 
having been taken to ensure stability. The results are ar- 
ranged according to the direction in which the needle 
pointed ; and the character of the daily deviation is distin- 
guished as follows. The reader must conceive himself as 
facing the north end of the needle ; then, when that end 
passes to his right hand the deviation is marked ( + ) , and 
when to his left hand ( — ) ; the bearing at six o'oclock in 
the morning being marked zero. 
