PROCEEDINGS. 
431 
Mr. 0. H. Tittmann gave a brief account of his summer’s 
work as one of the Commissioners on the demarkation of the 
Alaskan Boundary, which is 1200 miles long. A portion of 
this, some 500 miles long by 20 to 30 miles wide, had been sur¬ 
veyed by the photo-topographic method in previous years, and 
the results had been mapped for the High-Joint-Commission in 
London; this body had established the line, and the five field par¬ 
ties this summer began the work of erecting monuments to mark 
it. Much of the work was very difficult. [Not published.] 
Mr. L. A. Bauer then discussed A method of disclosing sys¬ 
tems of magnetic forces causing the secular variation of the 
earth’s magnetism. The forces that cause this variation are 
proved to act from the inside. From a discussion of observa¬ 
tions made in the United States from 1885 to 1895 it appears 
that the perturbing force operated in opposition to the forces 
producing the permanent field; that is, it acted as a demagnetiz¬ 
ing system. [Published in the Journal of Terrestrial Mag¬ 
netism, etc., vol. ix, p. 173, (1904).] 
589th Meeting. October 29, 1904. 
Mr. Isaac Winston in the chair. 
Thirty-one persons present. 
Mr. J. G. Hagen gave an account of Astronomy and mathe¬ 
matics at the International Congress of Arts and Sciences, speak¬ 
ing of the meetings, formal and informal, the foreign visitors, 
the papers, and the fine exhibits, especially of astronomical photo¬ 
graphs. Two great European gatherings kept away many of the 
expected visitors. [Published in Stimmen and Maria-Laach, 
Freiberg, Jahrgang 1904, Heft 1.] 
Mr. C. E. Van Orstrand then presented a paper on The load- 
strain function for finite strains. This curve is usually convex 
to the axis of loads, a short portion only being straight, as is as¬ 
sumed in Hooke’s law; between the points of rupture for tension 
and compression there can be no zero or negative values of the 
ordinates. The theory of functions enables one to define a priori 
all functions that satisfy these conditions. One of these func¬ 
tions, y = e cx where x is the load, y is the strain and e is 2.7183, 
