TEN YEARS' ALPINE TRAVEL (1774-84) 173 



sophers who lived some time before our Saviour's Nativity fixed 

 the perpendicular height of the highest mountains at about 

 10,000 feet.' Subsequent writers, he regrets, however, to have 

 to point out, have run them up ' to an extravagant and altogether 

 unnatural height,' owing to their preference of a trigonometrical 

 to a barometrical method. Scheuchzer dilates at some length 

 on the disadvantages which he believes to be incident to the 

 former method, and firmly asserts that the mountains of 

 Switzerland, though the highest hi Europe, do not rise above 

 10,000 French feet. 



Scheuchzer does not seem to have put his method into 

 practice. The next observer to try his hand on Mont Blanc 

 was Loys de Cheseaux, a Vaudois astronomer, who about 

 1744 obtained by trigonometry an elevation for the mountain 

 of 2246 toises above the lake, or 15,582 feet above sea- 

 level. 1 



Martel, the engineer, who visited Chamonix in 1742, got for 

 Mont Blanc by a trigonometrical measurement from a base of 

 1536 feet in the Chamonix valley a height closely corresponding 

 to Fatio de Duillier's. Early in the seventies, Deluc was busy 

 with his barometrical experiments and methods for the ascer- 

 tainment of heights, and combining these with trigonometrical 

 measurements from Geneva and the Buet he obtained for Mont 

 Blanc the height of about 15,285 feet, or some five hundred feet 

 too low. 



Dr. Paccard stated in the Journal de Lausanne that in 1786 

 he consulted his barometer on the top of Mont Blanc, but his 

 results were valueless, and Bonnet mentions that his instru- 

 ment was damaged. It is probable that some air had got 

 into it. 



There have been many slightly varying official determinations 

 of the height of the mountain in recent years. The latest, and 

 probably the most exact, is that of M. Joseph Vallot, based on 

 levelling from the Mediterranean to Geneva and on a most careful 

 triangulation. The result is 807 metres (15,771 feet), or only a 

 few feet higher than Shuckburgh's. The height of the snow-cap 

 probably varies by a few feet in different years and at different 

 seasons. It may therefore fairly be claimed for Shuckburgh 

 1 Traiti de la Comete, Lausanne, 1744. 



