Notes and Correspondence. 249 



Rainbow Bridge in Utah to be National Monument. 



Washington, June 3. — President Taft to-day, upon recom- 

 mendation of the Secretary of the Interior, issued a proclama- 

 tion creating Rainbow Bridge, a natural wonder within the 

 Navajo Indian reservation, near the southern boundary of Utah, 

 a national monument. Under the provisions of the national 

 monument act, 160 acres of land surrounding the bridge are 

 reserved for its protection. 



For further information concerning the great natural bridges 

 of Utah, see article by Byron Cummings in the National Geo- 

 graphic Magazine for February, 1910. 



The Altitude of Mount Huascaran. 

 In 1908 Miss A. Peck, of U. S. A., claimed to have ascended 

 the north, lower summit of Mt. Huascaran in Peru. She made 

 no instrumental observations above what she considers to be an 

 altitude of 5,975 metres (19,600 feet), but, from eye-estimates 

 only, asserted that this peak had a height of at least 7,317 metres 

 (24,000 feet), and was thus the highest mountain of South 

 America. 



Believing Aconcagua to be the highest Andean peak, and fur- 

 thermore to test the truth of these assertions, I decided to have 

 a careful detailed triangulation made of the two summits of Mt. 

 Huascaran. Through the assistance of Messrs. Fr. Schrader and 

 Henri Vallot, acting for the Societe Generale d'Etudes et de 

 Travaux Topographiques of Paris, an expedition was sent to 

 Peru for me under the direction of M. de Larminat to effect this 

 purpose. 



Assisted by the Peruvian Government and favorable weather, 

 M. de Larminat and his assistants were able to carry out this 

 work successfully between August and November, 1909. 



A base, 1,600 metres (5,248 feet) long was measured in the Rio 

 Santa Valley in the Black Cordillera at an altitude of 3,800 

 metres (12,464 feet). This base was measured by means of a 

 50 metre (164 feet) tape of Invar metal. From two stations, one 

 at either end of this base, and from two others, the positions 

 and altitudes of which were determined by trigonometrical 

 measurements from them, that is from four stations in all, the 

 positions and relative altitudes of the two summits of Huascaran 

 were fixed by azimuthal and zenithal angles taken by theodolite. 



In order to ascertain the true height of these stations above 

 average sea-level a progressive levehng was conducted from the 

 highest station, called the Garganta Signal down along the mule- 



