132 Lieut. Foster's observations on the diurnal changes 
of temperature, produced by the approach of the observer, 
or other causes, they were thickly covered with snow after 
every adjustment. 
During that part of the day when the needles suspended 
with floss silk indicated westerly variation, the direction of 
this needle is marked towards the right hand, when the north 
end passes to the right hand of a person standing outside of the 
compass-box, and facing the north end of the needle ; and to the 
left, when it passes towards the left hand. 
In the following details is given a short description of the 
adjustment of the magnets to the needle, at the commence- 
ment of the observations in each position of its north end ; 
and also the time in which it performed one vibration when 
under their influence, as well as the ratios in which the di- 
rective force was reduced by them ; but it must be remem- 
bered, that these ratios are mere approximations, since the 
directive force was always so much diminished, that a suf- 
ficient number of vibrations could not be counted, to estimate 
the duration of one with the required exactness. In the an- 
nexed tables every phenomena, such as halos, aurora borealis, 
winds, state of the weather, and position of the moon, are 
inserted ; together with such remarks, as suggested them- 
selves at the time of observation. There is also inserted in 
italics in the column of remarks ; max. easterly and westerly 
variation, opposite the hours at which they respectively took 
place by the suspended needle No. 2, in order to define the 
time of the day when the motion of this needle was towards 
the right, or left hand, as above described. And to point 
out the times of maximum westerly and easterly deflections 
of this needle, the signs -{- and — are prefixed to the hours 
of observation when they respectively happened. 
