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Scientific Intelligence. 
part of iron, as an alloy, would be sufficient to account for its 
magnetical qualities. Dr Wollaston has detected, by chemical 
means, a small quantity of Iron in Titanium, but not enough 
to account for its apparent magnetism. 
9. Experiments of Mr Barlow and Mr Christie on the Di- 
urnal Variation of the Needle . — Two very able and elaborate 
papers on this curious subject, by these two active and acute 
philosophers, have just appeared in the Phil. Trans, for 1823, 
Part 2d. 
From the minuteness of the daily variation, and the extreme 
difficulty of measuring it excepting with the nicest instruments, 
its laws, and consequently its cause, are still undiscovered. It 
occurred to Mr Barlow, that this deviation might be increased, 
both in the horizontal and in the dipping needle, to between 3 
and 4 degrees, by reducing the directive power of the needle, by 
means of one or two magnets so disposed, as to mask at least, 
in part, the terrestrial influence. Experiment proved this idea 
to be correct ; and Mr Barlow accordingly instituted a series of 
experiments. Mr Christie, to whom Mr Barlow communicated 
his views, also began the inquiry. 
Mr Barlow used a delicate and light needle, 8J inches long; 
and, by means of two magnets, he kept the needle balanced in 
different directions of the compass, and in these different directions 
he observed the daily changes in its position. The following were 
his results for the horizontal needle. 
When the N. end of the needle was directed to any point 
from the S. to NNW., its motion, during die forenoon, is to- 
wards the left hand, advancing, therefore, to some point between 
the NNW. and N. When the N. end is directed towards any 
point between the N. and SSE., it passes to the right hand, ad- 
vancing still to some point between the N. and NNW, Hence, 
there ought to be some direction between these limits, viz. be- 
tween the N. and NNW., and the S. and SSE., in which the daily 
motion is zero, or at least a minimum. Mr Barlow likewise con- 
cludes, that the daily change is not produced by a general de- 
flection of the directive power of the earth, but by an increase 
and decrease of attraction of some point between the N, and 
NNW., or between the S. and SSE. 
