WASHINGTON (AP) — A gauge designed to predict the economy's future health posted a solid increase in September after no gain in the previous month. The Conference Board says its index of leading indicators rose 0.8 percent last month following a flat reading in August which originally had been reported as a small 0.2 percent gain. Economists expect that continuing strong gains in employment should boost incomes and help support solid economic growth in the United States in coming quarters despite a weaker outlook overseas.