56 FINAL ACT OF SECOND PAN AMERICAN SCIENTIFIC CONGRESS. 



contained in Article 3, which are everywhere recognized as of interna- 

 tional importance. 



First, as to paragraph (a), which recommends a new determination 

 of the lunar parallax and of the flattening of the earth from closely simul- 

 taneous observations of the moon when on or near the same meridian. 

 It is known that the seventieth meridian of longitude west of Greenwich 

 passes through New England and through western Patagonia and affords 

 especially favorable conditions for nearly simultaneous meridian obser- 

 vations in these widely separated localities. The Observatory of Har- 

 vard University and the observatories of Argentina are not far from this 

 meridian, and hence could be immediately utilized in securing data for 

 additions to our knowledge of the mean distance of the moon and of the 

 surface shape of the earth. The resources of modern astronomy render 

 it quite practicable also to establish effective temporary observatories 

 without great expense on a given meridian and to secure thus strictly 

 simultaneous measures. 



Second, as to paragraph (6) of the recommendation. Of equally wide 

 scientific interest and of much greater utilitarian importance is a project 

 considered at length by the Section of connecting and covering the 

 states of the North and South American continent by a continuous and 

 uniform network of geodetic triangulation. When such a network is 

 completed its projection on a meridian will give an arc of about 126 in 

 latitude, while its projection on the equator will give an arc of about 153. 

 Such arcs will afford a contribution of the highest value in increasing the 

 precision of our knowledge of the dimensions of the earth. But the 

 greatest value of such a network of triangulation will consist in its avail- 

 ability as a basis for cadastral surveys and for the delimitation of state 

 divisional and interstate boundaries. 



Considerable progress has already been made toward the consumma- 

 tion of this project. The area of the United States is now well covered 

 by primary triangulation. Mexico has made much progress in covering 

 its area with a geodetic network. The famous Peruvian arc of meridian 

 measured by Bouguer and Condamine in the first half of the eighteenth 

 century has been recently remeasured and extended, while similar work 

 is projected in various Latin American countries and in Canada. 



Third, as regards paragraph (c) of the recommendation. Intimately 

 related to the two preceding topics is that of the desirability of extending 

 a gravimetric^ or pendulum survey over the areas not hitherto covered by 

 such work. It is known from theoretical considerations that the time of 

 vibration of a pendulum of given length or the length of a second's 

 pendulum at any place depends upon the mass distribution of the earth, 



