Bronze triangulation station mark, British, 1910-1920

Surveying

1910-1920

Bronze triangulation station mark, American, 1915-1920

Surveying

1915-1920

Bronze triangulation mark, French, 1910-1914

Surveying

1910-1914

Bronze triangulation station mark, Canadian, 1920

Surveying

Bronze triangulation station mark, Canadian, 1920

Surveying

1920

Triangulation mark, French, 1914

Surveying

1914

Bronze triangulation station mark, Canadian, 1920

Surveying

1920