In 1902, J. Jegerlehner, working in Bern, published a carefully compiled memoir entitled “Die Schneegrenze in den Gletschergebieten der Schweiz.” Footnote * This dealt with the distribution of the permanent snow and ice cover of our Alps based upon l’Atlas Topographique de la Suisse, the Siegfried Atlas, which was published about 1877 (actually from 1860 to 1890). The present Carte Nationale de la Suisse was brought out about 1932 (1918–44), a good half-century later. During this period our glaciers as a whole had not ceased receding except in a few cases here and there, so that it appeared essential to look into the state of the Swiss glacierization afresh. On the initiative, therefore, of the writer, with the helpful and indispensable assistance of the Service Topographique Fédéral, the Commission Helvétique des Glaciers carried out a planimetric survey of all the ice-covered areas shown on the new map. This very detailed work was carried out with great care by Herr W. Büla.
These areas, 72 in number, were distributed over 34 sheets of the map. As the surveys were spread over many years they naturally refer to varying dates, but in the main they were carried out during a time lapse of about twelve years, namely from 1927 to 1940. In order to determine with accuracy the total variation in an area surveyed over such a prolonged period it would, of course, be necessary to take into account the exact time of the initial and the final surveys. But to obtain a comprehensive picture of the extent of the ice in Switzerland, especially in view of the long lapse of time between the making of the two maps (1877 to 1932), this degree of precision was not absolutely necessary ; indeed the mere comparison of the total glacierized areas of former times and the present is, of itself, of great value to glaciology and world climatology. For this reason we have considered it opportune to give a total figure for the variation without waiting for the final details. Jegerlehner gave as his computation of the total glacierized area 1853 km.2. In 1932 it stood at 1384 km.2, a reduction of 469 km.2 (25 per cent)—a little less than the area of the Lake of Geneva, or about 3.3 per cent of the area of the whole country.
It should be noted that these computations refer to the glaciers seen as horizontal areas.
