Science owes to 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 410 HOW IT WORKS *** Produced by Jon Richfield *** START OF THE PROJECT GUTENBERG EBOOK THE INTERNATIONAL MONTHLY, VOLUME 4, NO. 4, NOVEMBER 1, 1851 Author.