This section is from the book "Mission Furniture: How To Make It", by Henry Haven Windsor. Also available from Amazon: Mission Furniture: How to Make It.
On some work it is quite difficult to locate the exact point for a dowel, but with the tool illustrated placed between the joint to be made and the parts gently pressed together you have the exact point for the dowel in each piece. The tool is made from a piece of sheet steel about 1/2 in. square with a pin having a point on both ends driven in the center, as shown in Fig. 1. The tool is placed between the pieces that are to be joined, as shown in Fig. 2. The small pin will mark the point for the bit in both pieces exactly opposite.
Marking Bore Holes for Dowels