In 1875 Lieutenant Weyprecht of the Austrian navy called the attention
of scientific men to the desirability of having an organized and
continual system of hourly meteorological and magnetic observations
around the poles. In 1879 the first conference of what was termed the
International Polar Congress was held at Hamburg. Delegates from eight
nations were present--Germany, Austria, Denmark, France, Holland,
Norway, Russia, and Sweden.
The congress then settled upon a programme whose features were: 1. To
establish general principles and fixed laws in regard to the pressure
of the atmosphere, the distribution and variation of temperature,
atmospheric currents, climatic characteristics. 2. To assist the
prediction of the course and occurrence of storms. 3. To assist the
study of the disturbances of the magnetic elements and their relations
to the auroral light and sun spots. 4. To study the distribution of
the magnetic force and its secular and other changes. 5. To study the
distribution of heat and submarine currents in the polar regions. 6. To
obtain certain dimensions in accord with recent methods. Finally, to
collect observations and specimens in the domain of zoology, botany,
geology, etc.
The representatives of the various nations had several conferences
later, and by the 1st of May, 1881, there were sufficient subscribers to
justify the establishment of eight Arctic stations.
France entered actively in this work later, and its first expedition was
to Orange Bay and Cape Horn, under the surveillance and direction of
the Academy of Sciences, Paris, and responsible to the Secretary of the
Navy. On the 6th of September, 1882, this scientific corps established
itself in Orange Bay, near Cape Horn, and energetically began its
serious labors, and by October 22 the greater part of their preliminary
preparations was completed, comprising the erection of a magnetic
observatory, an astronomic observatory, a room for the determination of
the carbonic anhydride of the air, another for the sea register, and
a bridge 92 feet long, photographic laboratory, barometer room, and
buildings for the men, food, and appurtenances, together with a
laboratory of natural history.
In short, in spite of persistent rains and the difficulties of the
situation, from September 8 to October 22 they erected an establishment
of which the different parts, fastened, as it were, to the flank of a
steep hill, covered 450 square meters (4,823 square feet), and rested
upon 200 wooden piles.
From September 26, 1882, to September 1, 1883, night and day
uninterruptedly, a watch was kept, in which the officers took part, so
that the observations might be regularly made and recorded. Every four
hours a series of direct magnetic and meteorological observations was
made, from hour to hour meteorological notes were taken, the rise and
fall of the sea recorded, and these were frequently multiplied by
observations every quarter of an hour; the longitude and latitude were
exactly determined, a number of additions to the catalogue of the fixed
stars for the southern heavens made, and numerous specimens in natural
history collected.
The apparatus employed by the expedition for the registration of the
magnetic elements was devised by M. Mascart, by which the variations
of the three elements are inscribed upon a sheet of paper covered with
gelatine bromide, inclination, vertical and horizontal components, with
a certainty which is shown by the 330 diurnal curves brought back from
the Cape.
The register proper is composed of a clock and a photographic frame
which descends its entire length in twenty-four hours, thus causing the
sensitized paper to pass behind a horizontal window upon which falls the
light reflected by the mirrors of the magnetic instruments. One of those
mirrors is fixed, and gives a line of reference; the other is attached
to the magnetic bar, whose slightest movements it reproduces upon the
sensitized paper. The moments when direct observations were taken were
carefully recorded. The magnetic _pavilion_ was made of wood and copper,
placed at about fifty-three feet from the dwellings or camp, near the
sea, against a wooded hill which shaded it completely; the interior
was covered with felt upon all its sides, in order to avoid as much as
possible the varying temperatures.
The diurnal amplitude of the declination increased uniformly from the
time of their arrival in September up to December, when it obtained
its maximum of 7'40", then diminished to June, when it is no more than
2'20"; from this it increased up to the day of departure. The maximum
declination takes place toward 1 P.M., the minimum at 8:50 A.M. The
night maxima and minima are not clearly shown except in the southern
winter.
The mean diurnal curve brings into prominence the constant diminution
of the declination and the much greater importance of the perturbations
during the summer months. These means, combined with the 300 absolute
determinations, give 4' as the annual change of the declination.
M. Mascart's apparatus proved to be wonderfully useful in recording the
rapid and slight perturbations of the magnet. Comparisons between the
magnetic and atmospheric perturbations gave no result. There was,
however, little stormy weather and no auroral displays. This latter
phenomenon, according to the English missionaries, is rarely observed in
Tierra del Fuego.
The electrometer used at the Cape was founded upon the principle
developed by Sir William Thomson. The atmospheric electricity is
gathered up by means of a thin thread of water, which flows from a
large brass reservoir furnished with a metallic tube 6.5 feet long. The
reservoir is placed upon glass supports isolated by sulphuric acid, and
is connected to the electrometer by a thread of metal which enters a
glass vessel containing sulphuric acid; into the same vessel enters a
platinum wire coming from the aluminum needle. Only 3,000 observations
were given by the photographic register, due to the fact that the
instruments were not fully protected against constant wet and cold.
Besides these observations direct observations of the magnetometer were
made, and the absolute determination of the elements of terrestrial
magnetism attempted.
On the 17th of November, 1882, a severe magnetic disturbance occurred,
lasting from 12 M. until 3 P.M., which in three hours changed the
declination 42'. The same perturbation was felt in Europe, and the
comparison of the observations in the two hemispheres will prove
instructive.
* * * * *