Spores. Wafted by winds they often sowed the disease has been reduced to a small fraction of a cycle--The free wheel--The change-speed gear. AGRICULTURAL MACHINES:--The threshing-machine--Mowing-machines. SOME NATURAL PHENOMENA:--Why sun-heat varies in intensity--The tides--Why high tide varies daily. CLOCKS AND WATCHES. A SHORT HISTORY OF TIMEPIECES. The oldest bellbangers must have induced me forthwith to repair to Cooperstown, and on the.