NavList:

   

Reply

In the March 1910 Geographical Journal is an article by Arthur R. Hinks,
"Notes on Determination of Position Near the Poles." It seems to be from
a lecture before the Royal Geographical Society.

"It is not a question of what observations might with advantage be made
but of what can actually be done. We will confine ourselves for the
present to the case of sledging equipment and sights to the Sun only."

On the question of sextant vs. theodolite, "recent experience seems all
in favour of the small mountain theodolite, as used by Captain Scott and
Sir Ernest Shackleton. Its obvious advantage is that by observing on
both faces the errors of adjustment are self eliminated... The sextant
and artificial horizon together weigh little less than the theodolite.
The sextant was found by Nansen to be unreliable in extreme cold; very
probably it developed error of eccentricity, which is very difficult to
determine. And observation of a low sun with an artificial horizon is
always difficult. Mercury horizons are apt to freeze; glass horizons do
not seem to give satisfactory results."

Following the presentation are extensive remarks by other members.
Observing on one face vs both faces is mentioned several times. The
"face" refers to the graduated circle where you read altitude. To read
the other face you rotate the telescope 180° about the horizontal axis,
then 180° about the vertical axis. Now it's pointed the same direction
as before, but the vertical circle is on your left ("face left") instead
of right, or vice versa. This reversal of the instrument cancels certain
errors.

https://archive.org/details/in.ernet.dli.2015.463878/page/n384/mode/1up?view=theater

The table of contents is at the end of the volume:

https://archive.org/details/in.ernet.dli.2015.463878/page/n994/mode/1up?view=theater

--
Paul Hirose
sofajpl.com

   

Reply