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.
THE ELECTRIC RAILWAY AT VIENNA.
The total length of this railway, which extended from the Eiskeller in the Schwimmschul-Allee to the northern entrance of the Rotunda, was 1528.3 meters; the gauge was 1 meter, and 60 per cent. of the length consisted of tangents, the remaining 40 per cent. being mostly curves of 250 meters radius. The gradients, three in number, were very small, averaging about 1:750.