336 Mr. Barlow’s observations and experiments on the 
having very obligingly undertaken to repeat my experiments 
at Spitzbergen, during the stay of the vessel at that place for 
the pendulum experiments ; and from which we may hope to 
derive some interesting deductions, particularly in reference 
to the influence of the direction of the solar rays ; for it is 
clear from the experiments reported in the preceding table, 
that the amount of the deviation does not entirely depend 
upon the moment when the heat of the sun is the greatest, 
as has been generally imagined ; for the time of the maxi- 
mum deviation varies from eleven o’clock in the morning to 
four o’clock in the afternoon, according to the direction in 
which the needle is pointed, and to other circumstances that 
will be mentioned in the conclusion of this article. Mr. 
Christie’s observations are also of a kind to throw great 
light on this subject. 
Another conclusion, which I think we are justified in draw- 
ing from the above experiments, is, that the daily change is 
not produced by a general deflection of the directive power 
of the earth, but by an increase and decrease of attraction of 
some point situated between the north and NNW, or between 
the south and SSE ( see the figure above referred to ) ; for I 
cannot conceive any other hypotheses that will account for 
two needles, situated as there shown, both approaching and 
both receding at the same time to and from the line of no 
daily variation ; nor for the total suspension or equivocal 
vibratory motion of a needle when placed towards this di- 
rection. 
I am sorry, that not foreseeing at the commencement of 
with which he selected the most appropriate situations for submitting that method 
to the test of actual experiment. 
