diff --git a/Mesh_2/changes.txt b/Mesh_2/changes.txt
index cc967454854..3c22c18ba40 100644
--- a/Mesh_2/changes.txt
+++ b/Mesh_2/changes.txt
@@ -8,6 +8,7 @@
   test/Mesh_3/combined_spheres.cpp.
 - major switch from .C to .cpp. Andreas's script left a lot of things that
 had to be fixed manually.
+- new header <CGAL/Mesh_2/Output_stream.h>
 
 7 July 2006 Laurent Rineau
 - add the ability to set the background color, and properties of the layer
diff --git a/Mesh_2/include/CGAL/Mesh_2/Output_stream.h b/Mesh_2/include/CGAL/Mesh_2/Output_stream.h
new file mode 100644
index 00000000000..d540be70724
--- /dev/null
+++ b/Mesh_2/include/CGAL/Mesh_2/Output_stream.h
@@ -0,0 +1,28 @@
+// Copyright (c) 2006  INRIA Sophia-Antipolis (France).
+// All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org); you may redistribute it under
+// the terms of the Q Public License version 1.0.
+// See the file LICENSE.QPL distributed with CGAL.
+//
+// Licensees holding a valid commercial license may use this file in
+// accordance with the commercial license agreement provided with the software.
+//
+// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+//
+// $URL$
+// $Id$
+//
+//
+// Author(s)     : Laurent Rineau
+
+#ifndef CGAL_MESHES_OUTPUT_STREAM_H
+
+#ifndef CGAL_MESHES_OUTPUT_ON_CERR
+#define CGAL_MESHES_OUTPUT_STREAM std::cout
+#else
+#define CGAL_MESHES_OUTPUT_STREAM std::cerr
+#endif
+
+#endif
diff --git a/Mesh_3/include/CGAL/Mesh_3/Double_map_container.h b/Mesh_3/include/CGAL/Mesh_3/Double_map_container.h
index 4f3b0029090..1d966faa0f5 100644
--- a/Mesh_3/include/CGAL/Mesh_3/Double_map_container.h
+++ b/Mesh_3/include/CGAL/Mesh_3/Double_map_container.h
@@ -21,6 +21,7 @@
 #define CGAL_MESH_3_DOUBLE_MAP_CONTAINER_H
 
 #include <set>
+#include <iostream>
 #include <CGAL/Double_map.h>
 
 namespace CGAL {
diff --git a/Mesh_3/include/CGAL/Mesh_3/Implicit_surface_mesher_visitor.h b/Mesh_3/include/CGAL/Mesh_3/Implicit_surface_mesher_visitor.h
index 640fee14d4c..6e1a09ad277 100644
--- a/Mesh_3/include/CGAL/Mesh_3/Implicit_surface_mesher_visitor.h
+++ b/Mesh_3/include/CGAL/Mesh_3/Implicit_surface_mesher_visitor.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2005  INRIA Sophia-Antipolis (France).
+// Copyright (c) 2005-2006  INRIA Sophia-Antipolis (France).
 // All rights reserved.
 //
 // This file is part of CGAL (www.cgal.org); you may redistribute it under
@@ -20,6 +20,8 @@
 #ifndef CGAL_MESH_3_IMPLICIT_SURFACE_MESHER_VISITOR_H
 #define CGAL_MESH_3_IMPLICIT_SURFACE_MESHER_VISITOR_H
 
+#include <CGAL/Mesh_2/Output_stream.h>
+
 namespace CGAL {
 
   namespace Mesh_3 {
@@ -50,10 +52,10 @@ namespace CGAL {
       {
         if(v->point().surface_index() == 0)
         {
-          std::cerr << "?";
+          CGAL_MESHES_OUTPUT_STREAM << "?";
           v->point().set_surface_index(1);
         }
-	std::cout << v->point().surface_index();
+	CGAL_MESHES_OUTPUT_STREAM << v->point().surface_index();
       }
 
       template <typename E, typename P, typename Z>
diff --git a/Mesh_3/include/CGAL/Mesh_3/Refine_tets.h b/Mesh_3/include/CGAL/Mesh_3/Refine_tets.h
index 35b78d83223..0397d7c1bdd 100644
--- a/Mesh_3/include/CGAL/Mesh_3/Refine_tets.h
+++ b/Mesh_3/include/CGAL/Mesh_3/Refine_tets.h
@@ -23,6 +23,8 @@
 #include <CGAL/Mesher_level.h>
 #include <CGAL/Mesh_2/Triangulation_mesher_level_traits_3.h>
 
+#include <CGAL/Mesh_2/Output_stream.h>
+
 //#include <CGAL/Mesh_3/Refine_edges.h>
 //#include <CGAL/Mesh_3/Refine_facets.h>
 
@@ -115,6 +117,9 @@ public:
 
   Point refinement_point_impl(const Cell_handle& c) const
   {
+#ifdef CGAL_MESHES_DEBUG_REFINEMENT_POINTS
+    std::cerr << "point from volume mesher: ";
+#endif
     typename Geom_traits::Construct_circumcenter_3 circumcenter = 
       triangulation_ref_impl().geom_traits().construct_circumcenter_3_object();
 
@@ -123,7 +128,16 @@ public:
     const Point& r = c->vertex(2)->point();
     const Point& s = c->vertex(3)->point();
 
-    return circumcenter(p, q, r, s);
+    const Point result = circumcenter(p, q, r, s);
+#ifdef CGAL_MESHES_DEBUG_REFINEMENT_POINTS
+#  ifdef CGAL_MESH_3_DIRTY_DEBUG_SPHERES
+    std::cerr << " \t\tdistance: " 
+              << CGAL::sqrt(CGAL::squared_distance(result, 
+                         typename Tr::Geom_traits::Point_3(CGAL::ORIGIN)));
+#  endif
+#endif
+
+    return result;
   }
 
 #if CGAL_MESH_3_DEBUG_BEFORE_CONFLICTS
@@ -213,7 +227,7 @@ public:
 
   void after_insertion_impl(const Vertex_handle& v)
   {
-    std::cout << "*";
+    CGAL_MESHES_OUTPUT_STREAM << "*";
 #if CGAL_MESH_3_DEBUG_AFTER_INSERTION
     std::cerr << "  INSERTED." << std::endl;
 #endif
diff --git a/Mesh_3/include/CGAL/Mesh_criteria_3.h b/Mesh_3/include/CGAL/Mesh_criteria_3.h
index c34c4372f63..1a50cce9faf 100644
--- a/Mesh_3/include/CGAL/Mesh_criteria_3.h
+++ b/Mesh_3/include/CGAL/Mesh_criteria_3.h
@@ -20,6 +20,8 @@
 #ifndef CGAL_MESH_CRITERIA_3_H
 #define CGAL_MESH_CRITERIA_3_H
 
+#include <iostream>
+
 namespace CGAL {
 
 template <typename Tr>
@@ -155,6 +157,12 @@ public:
 
 }; // end Mesh_criteria_3
 
+  template <typename Tr>
+  std::ostream& operator<<(std::ostream& os,
+                           const typename Mesh_criteria_3<Tr>::Quality& q)
+  {
+    return os << q.sq_size() << ", " << q.aspect();
+  }
 
 } // end namespace CGAL