There is no doubt that the fall of the dollar against other world currencies has helped American manufacturers by boosting exports and making imports more expensive. But it hasn't reversed the continued decline in factory employment, as might have been expected. The latest job numbers out this morning show that factories lost 46,000 jobs in April. The last month U.S. manufacturers added even a teeny amount of jobs was April 2006. Here is a chart of American manufacturing employment over the last decade. The Y-axis scale is in thousands, so for "18,000," read 18 million.